The following mains operated LED flasher circuit which is actually an astable multivibrator circuit utilizes only a diac and resistor arrangement for implementing interesting wig wag flashing of two LEDs.
The circuit was shared with me by Mr.Vineesh, who is one of the keen followers of this blog.
I would like to present the email that was sent to me by Mr.Vineesh.
The Circuit Objective
Dear sir,
Hope you remember me. i am not an electronics engineer,working as manager in a company, dealing basically with Tool & Die Enggr ,but self studying electronics for past 12-13 years,and have designed and made many simple projects of my own.
Some of them are marketed too.actually this entire ckt attached is not my idea.
I have gone thru 230V blinking LED circuit in some sites. i just converted it to alternate blinking. ckt working fine for last 2-3 months continuously. (used green bright leds)i know very well no need to explain the working of ckt. but just given 2 lines because if i am wrong in theory, you can correct me.
practically crkt is working well.while cap charging,led2, (series with cap) lights. DB3 get less than 30V while cap charging and does not conduct.after full charge of cap, diac conducts and led1( series to diac) lights,n cap discharge thru 1N 4007 ,that time LED2 light get dim ,which gives alternate blinking effect.
1.8K Resistor series to led1 is more than the requirement ,but given for matching the light intensity with LED2 all my ckts are drawn in note books, just selected one small ckt from that which is easy to draw in CAD & and convert pdf bcoz don't want to send shabby hand drawn drawings.
Thanks & Regards
vineesh
Analyzing the Circuit
Dear Vineesh,
Your explanation is absolutely correct, and the circuit is also very good, it can be well modified for ganpati, diwali, Christmas or for other similar decoration purposes. Good effort.
Thanks and Regards
Swagatam
Anonymous says
Hi, I find your website very intresting and usefull to have. Just one question, can I add more LEDs to LED1 and 2?
All the best,
Pravin
Swagatam says
Hi,
Thanks!
Yes you may do it, but the illumination will decrease as the numbers increase.
Abi says
Hi This blog is much batter then other websites in compare to circuit complicity ,i want a circuit that can drive room light according to people that comes in or out ,say for example if a person enters the room ,room lights start automatically and when person leaves that room it switch off it self in mean time person who is inside can switch it off manually and if next person enters that room light again glows.Considering when two or more people are inside if any one of them leaves that room light should not cut off.plz keep circuit as simple as possible
THANK YOU
Swagatam says
Hi,
I think you are referring to PIR controlled light system, you can make the last circuit given in the following link:
https://homemade-circuits.com/2012/10/how-to-understand-and-connect-passive.html
ELECTRO ASTRO TECH says
Sir kya ye d3 me 2 diode hai
Swagatam says
D3 is a diac DB-3, it's a different part.
Denys Handrei says
Dear Swagatam,
I need to do one array with 60 leds for my AC command of my car.
The 48 3mm blue leds use 3.2V 20mA each and the other 12 red leds need 2.2v 20mA each.
The problem is, my car use 17v with engine on and 15v with engine off.
I made a schematic pcb with L7808CV voltage regulator, this regulator can imput 0-32vin and following datasheet I left 8v stabilized with the capacitor. Following datasheet I left 8v stabilized out but it is heating up too much and do not have space for heatsink and it is heating up too much . Is there any alternative to this pcb with 8v stabilized without heat so much?
Thanks for any help.
Denys
Swagatam says
Dear Denys, A voltage regulator may not be required for 20mA LEDs
Let's assume the minimum supply level to be 12V, and max to be 17V, you will need to make 15 strings of LEDs having 4 series LEDs in each string along with a 270 ohm 1/4 watt resistors with each LED string. Connect all these strings in parallel with the supply input.
That's all, the LeDs will be safely lit with absolutely no heat.
Swagatam says
…sorry I missed the 3,2V LEDs, OK you can configure them in the following manner:
make 16 strings of blue LEDs having 3 series LeDs and a series 390 ohm 1/4 watt resistor in each string
and 3 strings of red LEDs having 4 series LEDs and a series 270 ohm 1/4 watt resistor in each string
Faith Jumbo says
Hello i really want to appreciate you, you indeed my hero when it comes to electronic. sir while i was going through the comments i noticed you said for 24v the ic741 should be replaced by lm321 and for another person you said he build the last circuit as it is for 24v please my question is can the last circuit work for 24v without modification because i have bought the components for it waiting for your reply before i start building thanks and best regards
Swagatam says
thank you, I think you posted under the wrong article.
however a IC 741 cannot run with a 24V supply so a LM321 is the recommended IC for a 24V supply