This programmable timer can be used for switching a load ON and OFF with two sets of time delays, which are programmable from 2 seconds to 24 hours independently.
The delay timings are adjustable according to the users personal specs. The ON time delay and the OFF time delay are independently settable and this facility becomes the most important feature of a programmable timer circuit.
Using Versatile IC 4060
In this page I will elucidate a very simple yet reasonably useful timer circuit diagram whose ON time and OFF time settings are independently adjustable through ordinary pots.
The idea becomes so easily configurable due to the versatile IC 4060 which require minimal number of component for getting the unit running.
Looking at the CIRCUIT DIAGRAM below we can see that two inexpensive IC 4060 have been wired up as two independent timer modes.
However though the timing settings are independent for the two sections, these are coupled with other such that their initialization become very much interconnected.
Basically both the configurations are similar and have been rigged in the standard counting modes of the IC 4060 devices.
You may also want to make this Arduino based programmable timer circuit
How the Circuit Functions
The output of the upper IC is coupled to the reset input of the lower IC via a transistor in such a way that once the upper IC's output goes high, it triggers the lower timer into operation.
The lower IC then starts counting and when its output goes high, it halts the upper ICs counting and resets it to its original state and the process is initiated back from the start.
It simply means that as long as the upper ICs timing does not lapse the lower IC remains idle, however once the upper ICs timing lapses and its output becomes high, it switches the output load as well as the lower ICs operation.
The pot associated with the upper IC can be used for determining after how long the load will be switched ON, while the pot associated with the lower IC is used for determining how long the load remains in the switched ON position or simply after what time it should be switched OFF.
Update:
The LED positions have been changed in the following updated designs, because the earlier LED positions were conflicting with the relay operations, and therefore the positions have been relocated for ensuring foolproof operations.
Circuit Diagram of a Versatile Programmable Timer
PCB Layout
Video showing the proposed 2-stage programmable timer circuit with LEDs
Using a Start Push-Button
The above design could be upgraded with a push-button to facilitate a push button start. This further ensures that the timer shuts off completely in case a power failure occurs while the circuit is operational, which in turn ensures that crucial loads like heater, or geyser are completely turned OFF during such situations.
Calculating RC Timing Components
It can be done through a formula, but the manual way is much simpler and accurate. It can be done as I have explained below:
- Connect any arbitrarily selected resistor above 100K in place of P1/R2 in the upper circuit.
- Switch ON and carefully note down after how much time pin#3 of upper IC 4060 becomes HIGH. This will be your "sample delay".
- Once this is noted, the other desired time delays could be calculated using the following simple cross multiplication:
Sample Delay / Desired Delay = Selected Resistor / Unknown Resistor
For example if you find the pin3 becoming high after 300 seconds, this becomes your sample delay value.
Now, we have the sample delay and the resistor value responsible for this delay.
Therefore if we assume the desired delay to be 1 hour or 3600 seconds, we can calculate it by substituting the values in the previous equation:
Sample Delay / Desired Delay = Selected Resistor / Unknown Resistor
300 / 3600 = 100 / x (unknown resistor)
300x = 360000
x = 1200 k or 1.2 Meg
This shows that 1.2 Meg in place of the P1/R2 will produce the required delay of 1 hour at pin3 of a IC 4060
Please note that the above calculation is only an example and the values do not indicate the actual results.
Customizing the Above Concept
This circuit of a flexible programmable timer circuit I have explained in this article was designed by me in response to a request by Mr.Amit. Let's know more about the request and the circuit details.
Technical Specifications
I need a circuit for my aquarium where it should do the following:
It should switch off the lights at 10:00 pm and start at 7:00 am daily + switch off the light at 12:00 pm daily and switch up at 6:00 pm back.
This will help to make my fishes live longer. 🙂
Thanks in advance.
Amit desai
The Design
So here's the circuit that I came up with. As the name suggest, the timer is pretty flexible and may be adjusted to produce any desired time periods, according to the above requested format.
The circuit consists of four identical stages, made up of the IC 4060 timer configuration. Te timer sequence begins from the IC at the top left corner.
When power is switched ON this IC starts counting. Depending upon the setting of its pot, the IC triggers after a certain period og time interval.
This switches ON the relay and the driver transistor BC547 which consequently switches OFF the connected lamp. The stage gets latched with the help of the diode connected across its pin 3 and pin 11.
The above triggering also switches another BC547 transistor which connects the reset pin of the next IC 4060 to ground which initiates this stage also.
After a predetermined time, this IC also triggers its output at pin3 and gets latched by the corresponding diode, however this actionsends a feedback signal to the relay driver transistor, instantly switching it off and restoring power back to the lamp so that it lights up again.
Just as the above actions, the sequence further proceeds and switches ON the third IC 4060 in the line which counts the set time interval and pulls the relay back to OFF position via the diode connected to the collector of its bc547 transistor, such that the lamp again gets switched OFF.
As soon as the above triggering happens the last section at the bottom right corner switches into action and counts as per the setting of the respective pot, until the ICs output becomes high, this high reset the the first IC and switches ON the lamp once again so that the process may be restart the cycle all over again.
The pots may be increased to 3m3 for generating higher time interval periods, so is true with the respective capacitors.
Circuit Diagram
How to Adjust and Set Up
The timer may be adjusted as per the sent request, in the following manner:
If we consider the first timing sequence to begin at 7am and end at 12pm, means the upper left timer's P1 needs to be adjusted such that it activates the relay and switches off the relay after exactly 5 hours.
For keeping the lamp switched OFF in the above position and switch it ON back at 6 pm we now adjust P1 of the upper right timer section such that its output triggers after another 5 hours. This switches ON the lamp again.
The above situation needs to be kept intact until night 10pm, which is about 4 hours of period, therefore we adjust the lower right timer's P1 to get it triggered after 4 hours of time interval.
Finally, for initiating the above procedure back again the next morning at 7am, P1 of the last timer at the lower right is adjusted such that it resets the first timer after 9 hours..... and the cycle repeats.
For making the circuit work according to the above specified timing pattern, after adjusting the respective hours, the unit should be powered or switched ON exactly at 7 clock in the morning....rest will automatically follow.
Cascaded Programmable Timer Circuit with Multiple Outputs
If you are looking for a programmable timer circuit having multiple outputs for controlling multiple loads and with individual time settings, then the following circuit will do the job for you.
Here, a 4-step programmable timer circuit is shown, but you can add more number of 4060 stages to increase the number of cascaded outputs, as desired.
The time delay output of each 4060 timer stage can be individually adjusted and set using the relevant P1 preset.
Questions & Answers
can you please make a circuit which will turn on led for 10 seconds and then turn off for 10 minutes
You can try the concept which is explained in the above article using IC 4060. Let me know if you have further questions.
Buna ziua domnule.In diagrama de mai sus cu cele două 4060 programabil timer circuit, unde pot pune led pentru clipire ca în video.Multumesc fiți binecuvantat
Gelu, You can put the LED between pin#14 and ground, or pin#15 and ground, through a series 1k resistor.
Hello once again.
I must apologize to you. My first request on the programmable circuit at 2 o’clock I L’ai formulated while I had not read this second page yet. would you not consider this first request?
Joseph
Thanks
No problem Joseph, Glad you found the right post for your specific application!
hi sir, I want to 5v power supply and 1 day 2 times timer ( 6:00 am switch on to 6:15 am switch off ), (4:00 pm switch on to 4:15 pm switch off ).Please support circuit diagram with ic4060 for me.Thank you.
Hi Min,
It will require a combination of 4060 IC and 2 or 3 ICs of 4017….but still the timing durations might not be accurate.
Thank you for publishing your design. I am an electronics tech myself, and after a number of hours repairing things on my bench, I tend to leave and forget to turn off my desoldering station or power supplies.
So what I want to do, is use a circuit that has a start button , that closes a relay for an adjustable length of time, say 2-4 hours. Then opens and saves my Hakko desoldering station or my power supply’s from being on all night… or days.
A reset button would also be helpful, as some times I am down in the shop for longer than 2 hours.
Your thoughts?
Sure, that makes sense.
Here’s a simple design which will fulfill your requirement perfectly:
You can increase the timing range by increasing the value of C1 appropriately to higher values, but it should be a non-polar capacitor only.
Please ignore the previous design and use the following instead:
The capacitor c1 can be a 1uF/50V or higher, non-polar type.
Hi dear swgatam
Me need minimum 500 milisecond.
R1,R2 and C1 what tobe
Thanks
Hi Ismail, for a single timing output you can use a 555 timer instead.
Dont single,ı want 1 munite off 0.5 sn on for filter cleaning valve.
In the article I have provided the method to calculate the part values, please follow that procedure, you should be able to identify and select the right parts as per your specification.
Thanks dear you Are perfect
Thank you, it’s my pleasure!
Sir, Thanks for yu patience in replying. I have got a request. I am using bore well motor having starting capacitor and running capacitor and i want to automatically switch it on. As you know that once power is given starting capacitor will be in closed circuit for 3 to 5 seconds and should disconnect after that. Is there any simple circuit which can replace the function of push button presently used?
Thank you Ravidran,
To keep the capacitor of the motor energized for a few seconds you can try implementing the following circuit:
The relay N/O contacts must be wired in series with the capacitor connection.
The 100uF capacitor and the 22k resistor values can be experimented to change the delay period as required.
The transistor can be a BC547 transistor.
This is the first time i am getting a guidance on a u tube chennal. Thanks for your quick response. I have started assembling cycles timer using CD 4060 published by you. I will make it success with your support. I do have some project. Pl share your email id.
Thank you Ravindran, i will try to help you as much as possible until you succeed.
We can comfortably discuss through this commenting platform so that other readers are also ale to go through our discussion and learn more about the subject.
Its better for me if you mention transister pin nane, like emiter collecter and base, i want to leqrn, i already maked for delay off for qs long i want, but problem is its not automatically on after 3 or 4 hrs, ppease support me……
You can checkout the BC547 datasheet below and compare the pinout details:
https://www.homemade-circuits.com/quick-datasheet-of-bc547-transistor-45v-100ma-npn-transistor/
Hello sir, hope all is going well. Sir i need your kind support. O want to diacuss about timer on and off circut. Sir can you give me a favor plz. Can you guide me resiaters, caposter valies as per cd4060 ic pin configration timing? Lile pon no 3 is for 8 to 24 hrs. Which resiaters and caposter value and pot value we have to use for same timer plz
Thanks in advance
Hello Ghulam,
There’s no accurate formula to calculate these values. You will have to find it yourself with some trial and error and using the cross multiplication formula given in the article. Please follow the steps provided under the title “Calculating RC Timing Components”
Hello sir, sorry to disturb you again. Sir, I am facing an issue in timer circuit. It works fine for almost 2 or 3 days, but after 1 or 2 or 3 days randomly it gets stuck on delay off section. I chose pin no 1 of CD4060 for delay and pin 3 for on time. 2 capacitors 22 uF as a polar capacitor I used on pin 9, 100k on pin 10 with 500k pot, and pin 11 used 2.2 mega ohm 2 resistors in series. While working, it worked fine but got stuck some time on delay section. Please guide me why it happens?
Hello Ghulam, do not use polarized capacitors. Please use only non-polarized capacitors. You can use 22nos of 1uF/100V PPC capacitors in parallel to get an equivalent 22uF non-polar capacitor.
Sir thanks for reply. Sir can i put 5mm led with 100ohm resister for pulse on pin no 7 for both ics seperatly? Or of there is any other way plz guide me
Ghulam, pin#7 will produce very fast pulse, which cannot be distinguished on the LED, instead you can use pin#15 or pin#14. Use 1k series resistor.
Its more easy if you make vedio on breadboqrf for me please.its request sir plz
Please don’t try on breadboard because breadboard can have loose connection problems, build it on a perfboard by soldering.
Dear sir, i want yo make timer for 20hrs load on and 4 hrs off. This cycle work automatically daily. Plz support me with simple diagram plz
Hello Ghulam,
The diagram is already given in the above article. You can try the first diagram.
However please do not attempt this circuit if you are a newcomer to electronics.
This circuit is recommended only for those who are reasonably expert with electronic circuits
Thanks for reply, sir i tried and its work for same time on and off, like only almost 10 seconds its on and off, i changed the resister values and pot to 1 m woth pin 10, but same. If i will not try then how i will learn, plz guide me b3cause i want to learn…..as i told you i alreqdy maked for delqy off as i want. With accurate time, but after load off not comes on automatically, i need solution for that load will on after our setting time. Plz
Hello Ghulam, The first circuit in the above article is a tested design and it worked for me perfectly.
If you are confident that you can build it then you can try the circuit step-wise. First build the upper 4060 IC stage with the BC547 and the relay as shown in the following example design. If you succeed with this, then you can add the lower 4060 stage to it and check how it works:
Yes sir i tried and this uper circut is working, now how to add 2nd ic, can you make seperate diagram plz,
Ghulam, The diagram is already given in the above article. Please see the first diagram and see how the lower IC is configured with the upper IC.
Hi sir, lot of thanks for your support. now its working, thank a lot
That’s great Ghulam, glad it is working now.
Thanks for your passion to guide me…….if some one have good teacher like you then nothing is impposible. I cleared impossible mistion due to you. Thanks a lot
You are most welcome Ghulam, Please keep up the good work!
Can I use your above circuit to switch on at 6.30pm and switch off at 10.00 p.m. please?
Yes, that’s possible but the timing will not be accurate always.
Hi Swagatham
Can you please send me the circuit of the 4060 IC timer circuit for a 1 to 2 hours or more for time delay relay OFF
Hi Val,
Here’s the link you are looking for.
https://www.homemade-circuits.com/how-to-make-simple-versatile-timer/
Great article, Swagatam. I’m not too au fait with modern electronics, so please bear with me.
I’m basically wanting to switch an ultrasonic mister, powered via a mains transformer giving 24v rated at 1.0amps, on and off every 5 minutes or so (still experimenting) to control humidity in a small enclosed space I’ve constructed for a plant.
It appears to me that this circuit would do the job, but I’m unsure of several things which I hope you’ll be able to answer for me
ie what type of relay to use, what range of resistor values would you suggest I use as I’m starting from scratch, and whether It’d be feasible to tap into the 24v supply for the mister to power the circuit, using some form of voltage reduction (simple series resistor perhaps?).
Could a potentiometer be used in place of experimenting with various resistors, as the timing is not millisecond precise, and what range would you suggest please?
Thank you Peter,
If your ON/OFF time are equal and there’s no need of trying the above explained complex 4060 circuits. You can simply achieve it using a IC 555 timer circuit as explained in the following article:
https://www.homemade-circuits.com/alternate-switching-relay-timer-circuit/
You will only have to experiment with the 470uF capacitor for getting the 5 minute ON/OFF delays for the relay.
Please ignore the second load connected with the relay….you can use only one load as desired by you.
All resistors are 1/4 watt 5% CFR
Thanks for your prompt reply, Swagatam, and I appreciate you directing me to the other circuit.
However, as I’m still experimenting with timings, I think I would prefer to have the versatility of choosing different times for the on and off periods, so feel.
So could you please advise accordingly?
OK no problem, here are the answers to your previous questions:
Resistors are all 1/4 watt 5% CFR
Relay can be any 12V SPDT relay with a coil resistance between 200 ohm to 400 ohm.
To extract 12V from 24V supply , you can use a 7812 voltage regulator IC.
You can use a potentiometer only for P1 and P2 and vary the time delays as per the adjustments.
Thanks again. As I have no resistors in stock, I was hoping for some guidance on what values to purchase in order to achieve my aims. Alternatively could I substitute P1/R1 and P2/R2 with 1meg linear pots (+/- 20%) to achieve my aim, or would that not be high enough (the largest value I’ve found so far is 2M2 with a +/- 30% tolerance above 1M).
As I said, I’m not too familiar with modern electronics, but would it simply be OK to take the output voltage direct from the regulator (it has a tolerance of 2 to 4%) without any extra components?
All advice greatly appreciated.
You can replace the components at pin#10 of the IC with a 1M pot and a 10K series resistor. With C1 = 1uF you can get significantly long delays at pin#3 of the IC with these values at pin#9 and pin#10 of the IC. The remaining resistor values can be as is.
If you have good filtered DC input at the input side of the regulator then you do not have to add any other components at the output of the regulator. With a 24V input and 12V output your regulator can get very hot, so a heatsink may be required for it.
That’s excellent – thanks! As far as the 24dc supply goes, all I know is that it’s a standard mains direct plug-in transformer with 24v 1a rating made in China. Not sophisticated, but could it do the job? If not, any suggestions welcomed.
No problem, you can check the output of your adapter with a meter to confirm whether it is a pure DC or not. If it is a DC then the 7812 regulator will require no additional components for its configuration. Hopefully it should be an AC to 24V DC adapter
Yes it is 12v dc, so I guess I can go ahead!
Thankyou so much for your prompt answers and patience in dealing with my relatively basic queries!.
You are welcome, I am always glad to help!
Can I use the IC4060 timer circuit shown here only to turn a small electromagnet on and off for specified and adjustable millisecond periods of time? An example table is below. Don’t need quite the high accuracy indicated here.
Time (milliseconds)
On Off
1.09 | 28.91
0.55 | 14.45
0.36 | 9.64
0.27 | 7.23
0.22 | 5.78
0.18 | 4.82
0.16 | 4.13
0.14 | 3.61
0.12 | 3.21
0.11 | 2.89
Yes that’s possible. You would need two 4060 ICs for that. However adjusting to the milliseconds could be very difficult.
Hello Swagatam,
I’m glad it all cleared up, no harm was done.
From what I’ve read, one of the biggest disadvantages of transformerless power supplies is that they don’t protect the circuit they feed from electrical interference of any kind, without adding additional electronic components, which are either expensive or hard to find, end up increasing the complexity of executing a circuit.
Since it is a circuit with ICs and for better protection, I would like to ask if it would be possible to supply your circuit (using the TRIAC version) with a 230V/9V/1.5 VA transformer, as I have found a lot of them in emergency luminaires that have all been replaced by LEDs, and whose circuits are all functional. Do I need to rectify, filter and stabilize this power supply before feeding it to your circuit?
How would the 2 electrical diagrams look like?
Thank you in advance.
Best whishes,
Thank you Joao,
If you don’t wish to have a transformerless power supply, then the configuration woud become like this:
To this circuit you can supply a 12V DC from a transformer power supply with a full bridge rectifier and a filter capacitor or from an SMPS unit. The negative of the power supply will connect with the line that is marked with the ground symbol (line connecting the pin#8 of the ICs).
The bridge rectifier can be build using 4 diodes, and the filter capacitor can be a 1000uF/25V. You can include a 7812 IC for stabilization if you have one, which will ensure better working of the circuit.
Hello Swagatam,
In the circuit “
” that you suggested, what would happen when connecting the 230 Vac mains supply , if I connected de L to the DC ground’s circuit and N (neutral) at the other end of the load?
I don’t know if it is implicit or not, in the article “Simple Triac Triggering Circuits Explained”, but I can’t find the answer to this question.
In Portugal and other European countries, it is not necessary to connect the L and N electrical conductors of the mains supply on the same side in the sockets, as the plug can be inverted.
Best wishes,
Hello João,
The Live/Neutral polarity is not critical in the specified triac circuit, you can connect the L/N any way round as you wish, it won’t have any affect on the working of the circuit.
But be very careful with this circuit, since the circuit is not isolated from mains AC it can be lethal to touch in part of the circuit in open and powered ON condition.
Hello Swagatam, thank you for your reply.
a) In the aforementioned circuit, is there any of the electronic components that need to dissipate more heat and therefore be greater than 1/4W or 1/8W, and the triac will need a heat sink?
b) To test the mentioned circuit with 12V DC, which components must be changed and what are their values?
Very soon I will share photos of the circuit that you helped me to build, using the email.
Best wishes,
Hi João,
Nothing will dissipate heat in the circuit, so no changes are required, all resistors can be 1/4 CFR. The triac BT136 may require a heatsink if the load is higher than 100 watts.
The circuit is intended to work with 12V, so nothing needs to be changed.
Sure, if you succeed with the project, please do send the pictures, I will add them to the above article.
Let me know if you face any issues.
Make sure to test the circuit without a triac and load, and only with LEDs, with one LED across pin#3 of each IC and ground. The LEDs must have a 1k series resistor.
Hello Swagatam, thank you for your reply.
What I intended to say by testing the circuit at 12vdc was the following: Assuming that the triac behaves like a switch in the ON state, if instead of using 230Vac, I use the same 12Vdc used to power the circuit, can I use as a load, for example a fan or an LED?
Best wishes,
Thank you João, the triac will latch once turned ON and will not turn off until power is switched OFF, so it won’t work with a 12V DC.
But you can use 12V AC from the transformer wires directly, that will work. Just replace the 230V AC with 12V AC, and the load can be an LED with series resistor.
Hello Swagatam, thank you for your reply.
Ok, I will use your suggestion, as it is much, much, much safer.
Best wishes,
No problem João,
please let me know how it goes.
Hello Swagatam, thank you for your reply.
Please clarify, what you are saying is that it is not possible to supply this circuit with a 9V transformer; 1.5VA , (about the meaning of 1.5VA, I will put the doubt about its meaning, in the category “https://www.homemade-circuits.com/how-to-make-transformers/”)?
Because it would imply new calculations of the electronic components used, and/or in this circuit reducing the supply voltage, would make the operation unstable?
It will be possible to use it, using a ZENER of 12V/1W (or less), also calculating its series resistance, instead of IC7812, the final voltage after rectification and filtering will rise above 9V, believe it will be sufficient/efficient ?
Best wishes,
Hello Joao,
The proposed programmable timer circuit using triac can work with any voltage between 5 V DC and 15 V DC. The ideal value is 12 V DC. If you use a 9V transformer with a full bridge rectification, that would produce around 9 x 1.41 = 12.69V or 13 V peak, which may be just sufficient for the circuit to work efficiently. Slight fluctuations in the DC will not affect the working of the circuit. However, for better accuracy you can include a 7812 IC. A zener diode will not work and could burn due to over current. Using a limiting resistor for the zener might reduce the gate current for the triac and might cause triggering issues for the triac. Nevertheless, you can try using a resistor with the zener diode and see if that works OK or not. The resistor value can be arbitrarily selected as 470 ohms. If you want to calculate it perfectly then you can refer to the following article:
How to Calculate Zener Diode Resistor
Hello again,
I forgot to ask which TRIAC do you think is suitable for this application (5W/240V=0.021A or 21mA), for ON/OFF rhythmic operation? There is so many part numbers…
Best wishes,
You can use BT136 triac, it is a very common 1 amp 300V triac and may be easily accessible for the local market.
Hello Swagatam, thank you for your reply.
Best wishes
You are welcome Joao!
Hello Swagatam, thank you for your reply.
Well then the IC 7812 will be. Do I need to apply a heatsink to it?
What will be the expected current consumption in the TRIAC version of your circuit?
If the current is more than (1.5VA/9V=0.17A or 170mA), then “Houston, we (I) have a problem”…
Best wishes,
Hello Joao,
The consumption will not be more than 20 mA, so 170 ma is more than enough for the circuit.
Heatsink will not be required for the 7812.
Hello Swagatam,
The 1st place I tried to find the IC 4060 data sheet was here in this knowledge sharing space, but without success (sorry if I didn’t see it).
The 2nd was on the net, but I found so many different designations, that I was confused. I found several letters before and after the reference 4060, which left me in doubt if it is the same IC. Can you explain to me how I should analyze these same datasheets?
Best wishes,
Hello Joao,
The prefix after the 4060 is not important. Meaning, you can use any 4060 IC that you can get. The number 4060 is the only important thing that needs to be considered on the IC. All 4060 ICs should work in the same way. So you can refer to any 4060 datasheet, the specifications will be all the same.
Hello Sir,
I would like to ask you if is it possible to replace the relay with a Triac and make the circuit without transformer? So it can be assembled inside small electrical outlet to control a mosquito destroyer (240V AC/5W).
Thank you in advance
Hello Joao,
You can try the following modification:
Dear Swagatam,
Thank you for your fast reply. I´m going to try it, as soon as possible.
Please clarify me, the green LED is going to light up, at the same time as the TRIAC switch ON, or will it work as a standby indication, turning OFF when the TRIAC turns ON?
Do you believe it is not necessary to stepping down and rectify the AC mains, before de Zener? If so, is it sufficient 1W or do I need more?
Best wishes
You are welcome Joao,
The green LED will light up when the triac switches ON, and will remain switched OFF as long as the triac remains switched OFF.
The AC mains will be stepped down to 12v due to the presence of the 0.33uF/400V and the 12V zener diode, so no need of any additional circuit. Since the 0.33uF will be able to generate only 25 ma current, a 1 watt zener should be quite sufficient according to me.
Hello again,
So just because it’s only 25 mA, you don’t need a resistor in parallel with a 0.33uF capacitor either.
Best wishes
You can put a resistor parallel to the 0.33uF/400V capacitor to ensure that the capacitor is quickly discharged whenever the circuit is unplugged from mains AC. This maybe helpful to avoid a possible electric shock from capacitor discharge. However, this resistor has nothing to do with the working of the circuit.
Hello Swagatam, thank you for your reply.
Can you teach me how to calculate this resistance, in a simple way? I read (I don’t know where) that it can also serve as a fuse, is that true?
Thant you in advance.
P.S. Please tell me where I can ask my questions about LED power supplies.
Hello Joao,
I do not have the formula for calculating the resistor parallel to the 0.33uF capacitor. However, it is not required anyways, because any resistor between 330K and 1M should be able to discharge the capacitor in less than a second, so calculating may not be crucial.
No, it will not work like a fuse since it is not positioned to work like a fuse.
For LED power supply you can ask under the following article:
https://www.homemade-circuits.com/how-to-design-simple-led-driver-circuits/
Hello Swagatam, thank you for your reply.
Best wishes.
My pleasure Joao!
Would the circuit above need to have P1, R1, R2 and C1 changed in order to have the timers do minutes, instead of hours?
Only P1 and C1 needs to be changed in order to change the output delay. Alternatively only one of these could be changed for the same.
hi dear sir
i need a timer circuit that start a pump on via relay for 2 hours to circulate water of pool then off for 22 hours and again on the pump for 2 hours .repeat daily.
thanks a lot
Hi Abbasali,
2 hour ON and 24 hour OFf can be difficult to adjust, instead the timing can be adjusted to 144 minutes ON and 1296 minutes OFF.
como se instala una tarjeta que usa un CI MC14541BCP DE HORNO TOSTADOR TOASTMASTER MODELO 357S SI PUEDE INVIAR DIAGRAMA
Sorry, I do not have the information with me regarding How to install a card that uses an IC MC14541BCP OF TOASTMASTER TOAST OVEN MODEL 357S
Dear Sir,
Need circuit design for solenoid valve working. the case is that I have 2 switches, once I push on left switch it should on the left one solenoid valve and when I switch on right one the right one solenoid should work. once both switches are on then left solenoid valve should work. can you give me pcb circuit design for that. It will be great help for my project.
Thanks
Arun
Dear Arun, What is the specification of the switch? Is it SPST switch or push button type?
Dear Sir,
In addition I measured voltage between PIN3 and PIN8 shows 0V. Between PIN3 and GROUND of circuit shows 5V on both ICs. Relay is not activated and both LEDs are glowing for ewer.
Dear Sir,
Thank you very much. It works perfectly.
Nedzad Niksic
Thanks Nedzad, glad it is working now!
Dear Sir,
I copied your PCB layout and assembled the circuit exactly as it shows on PCB layout components drawing. All capacitors are 1 microF. For C3 I used tantalum. When power ON the relay is activated immediately and both LEDs are ON for ewer. When I change transistors PINOUT (here in Bosnia, you newer know who is manufacturer of such small transistors, so the PINOUT is problematic) the relay is not activated, but both LEDs are ON for ewer. Please HELP. I need the circuit that activate the relay twice a day for 2 minutes to water my plant.
Hello Nedzad, please do not rely on the PCB design since it was designed by an external source, and it might have problems.
Please build the circuit on a veroboard first according to the given schematic, and confirm its working, and then get the PCB designed from a professional designer.
The circuit is thoroughly tested and will work without any issues.