Brief Introduction
Homemade circuits was founded in the year 2011 by Swagatam, initially it was started in blogger.com and then migrated to wordpress. Prior to this the author used to work as a content writer in Brighthub.
Homemade circuits was started with an aim to share and spread the knowledge of electronic concepts freely among the aspiring engineers and newbies, through the expertise of experienced authors involved with this site.
What we do
Since the author of this site is too passionate about researching electronic concepts and innovative circuits, the main objective here has been to share the new ideas and results with other like minded hobbyists and engineers.
As we know electronics is an intriguing subject, and no doubt all want to write about its theories and concepts.
The online world is flooded with multitude of electronic websites offering free electronic circuits and stuffs, ....but unfortunately there's one thing they mostly seem to lack, and that's credibility.
An electronic idea is not just about publishing a piece of schematic and forgetting, or posting something too technical without an elaborate and convincing explanation.
We Actively Respond to Questions Because We Know the Answers
Here at homemade circuits, unlike others we make sure that the author who is writing the post has an in-depth knowledge regarding the subject, and actively responds to every comment or query posted by a inquisitive visitor.
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Enlightening the new users with clear and authentic information is the main motto here.
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In this site you will find that no electronic concept is unnecessarily made complex just to make it look more advanced. We always try to produce an easier alternative if feasible, so that even a layman can feel inspired to learn more.
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Hello There,
I’m seeking help designing a simple low voltage low current relay contact OPEN detector circuit (which I’ll put in a project box). I need a circuit that can detect when a relay contact that is normally closed, opens across it’s two output pins. Once the circuit detects this new OPEN state at the input, I need to (using your new transistor or opto-isolator? circuit) provide a contact closure as an output which will simply pass a GND signal thru its relay contacts in another unit I’m controlling.. If the Input then contacts then close the output relay contacts of the circuit need to OPEN again. I want to use a small 5 volt Normally Open contact relay
to provide the output contact Closure when its detected and activated but am not sure of a simple way to detect when a relay contact opens. I can provide it either +5 or +12vdc to power the Open Contact Detector circuit. Thanks in advance .. JimS
Hi, I am not sure if I correctly understood your requirement, still I have made an effort to solve it through this diagram, please check it out…
https://www.homemade-circuits.com/wp-content/uploads/2019/10/relay-detect.png
Thank You I think the Open switch Contact detector you provided at the link above will work if I give it a Vcc power source so I will try it with the +5.5 vdc supply I have via 10K ohm potentiometer connected to the BC557 Emitter across it to the Vcc RTN line at the bottom and see if that will allow the 160 ohm relay coil to actuate as the input switch contact opens, if not, I will lower the pot-resistance till it does.. I’d send a image of this minor mod if I could but the site won’t accept it. Thanks for your help
No problem…The best way to show an image is to upload it in any “free image hosting site” online, and then provide the link to me here, so that I can check it. You can also do the same through Google drive. Remember not to include the https, or http, otherwise the comment will be moved to SPAM.
Ok I think I understand.. Can you help me find a web site that will allow me to create simple schematics (like yours) ( ideally for free) then post them to a free image hosting site as you suggest? By the way, is there any easy way to find my posts here again later ? I’m not sure I’m posting in the proper locations on the site either but this “About Us” area was the only one I found would allow me to enter the question I’ve posted above. I see no way to put in in a more appropriate group/topic area.. is that all process managed / and filtered by your moderators?
You can post under any article involving relays or transistors.
Ok so set up an account on imagur and believe this may be the link to the Rev 2 DRAFT schematic update..
imgur.com/LvgoaD7
Please tell me if this will work and if I can simplify it.. I do need a simple contact closure only (not an open collector driver) output when it detects the NC contact Opens at the input J4.. But, I don’t think I need all the resistors as shown, nor know what values they should be. I have a A928A PNP and a digikey PN 725-1354-ND Reed Relay in hand but can substitute parts. Thanks again for the help .. JimS
The diagram is not correct, I have shown you the correct diagram previously. It should be exactly as I presented, as per your design specs.
Mr Swagatam,
could you take another look at the diagram you sent previously? I hate to disagree but don’t see how can work with absolutely no Vcc or Return reference. That is the only reason I tweaked that modification into it, to add a voltage source, that and to try to bias the transistor properly with it added in. I have a 5.5 vdc and RTN I could use to provide a potential across the transistor but right now all we have is a NC contact that will OPEN to trigger the event, and a Normally Open pair of input pins on the circuit’s OUTPUT side that need to see a contact closure (and I can’t use an open collector driver or apply any voltage to them, I need a contact closure at the output but don’t understand how or why the BC557 ( or any other PNP like the A928A I substituted) can work without some difference in potential to drive the relay’s coil current. Can you explain that please? Thank you again for the assist. I can try to move this over to a transistor or a relay thread if you wnat me to try, but I did not see any open “Comment” dialogue for any new entry when I looked there before submitting it here in the “About” thread.
Hello Jim, it is obvious that the upper line or the emitter of the PNP must be connected to Vcc, I just forgot to show it in the diagram. If there’s no supply then how will the relay operate?
Similarly the lower line which is connected with the 1N4148 and relay is the 0V line and must be connected to the Vss or the negative of the power supply
I am 60 years old and just getting interested in this kind of stuff. You may already have this on your site and I missed it. I would like to build chaser lights that stay lit until the end of the sequence then either blink or flash then start over. I would like to use them as turn signals on my Jazzie. Thank you. John
Thanks, I’ll try to figure it out and post the idea soon for you!
Hello sir,
I want some help from you. In my project where i stuck. The problem is – I want a 3 phase sequence detector using microcontroller (Atmega-32) without neutral. I referred https://www.researchgate.net/publication/301478340_Micro-controller_Based_3-phase_Sequence_Indicator . But I didn’t understand programming logic of phase AB(); phase Bc(); phase CA(); Please help me.
Sorry Danish, I am not good with microcontroller coding, so I won’t be able to help you in this regard.
Sir swagatam, can we earn money for writing article on your blog?
Hi Aabhishek, I am sorry, presently I am not publishing contributions from writers, in future I may surely consider about this and then I may contact you.
Hai Swagatam,
apakah Anda memiliki rangkaian led sequential dengan menggunakan IC 74LS164 ?
Thank You
Halo Heru
Anda dapat merujuk pada artikel berikut: https://www.homemade-circuits.com/knight-rider-led-scanner-circuit/ Ini dapat menyelesaikan kebutuhan Anda