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Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.


  1. Lucky-Luka

    3.3V microcontroller vs 5V relay

    Hi all I was looking for a relay board to be used with my 3.3V Arduino board. Relay module I know this isn't a proper relay to drive inductive load at 220V. I have read that it can be controlled with 3.3V GPIO pins. I will try to do a test but before that I would like to hear your opinion. This...
  2. S

    Need assistance with Relay options

    Hello, I am brand new to this forum and hope to further my limited education in DC electronics. I am attempting to put together a simple "auto" switch to move from a primary DC power source to a backup DC power source if the primary power fails. Here are my components: Primary Power - 12V...
  3. T

    12v circuit that stops power output when source power lost

    I'm looking for a circuit to install in my car from my battery to my subwoofer. When I turn on my car I get feedback for a few seconds. I've created a solution to this by installing a rocker switch inline with the power source cutting power to the subwoofer when I need to. I often forget to turn...
  4. hesam_m

    IR Remote Control Switcher using an ATTiny85 MCU

    Infrared remote controllers are everywhere around us. The majority of home appliances are controlled using infrared remote controls. In this article/video, we learn to build a device that can decode (almost) any IR remote control and use the instructions to switch the relays (loads). So we can...
  5. E

    Can two N-Channel MOSFETs be connected in series to perform a "AND" function?

    Hello, I'm designing a circuit to ring a bell using a code set by the user. When powered the circuit steps through the code which is set via DIP switches to decide where a "ding" or a space should be within the code. Each "on" position within the code actuates a modified car relay which hits...
  6. A

    What can of relay or system do I need to use for 7000V rat trap?

    Please forgive if some information or diagrams are missing, I will provide any information you consider necessary if you ask for it in the thread. As you might soon discover I have no background/knowledge in electrical engineering. I will start working on a project to build an electric rat...
  7. E

    BJT or MOSFET for 4017 Relay Driver Circuit retaining High-Level Logic Output

    Hello there, I'll start by saying I'm by no means an expert in electronic design, so please bear with me. Also my schematic and the datasheets I'm using will all be attached to this post. I'm designing a circuit whereby the output of a 4017B IC is driving a relay via a BC337-25 BJT Transistor...
  8. A

    4-20mA to adjustable set point relay

    Why does this not work? I can adjust the pot and the relay will energize. The 4-20mA will not energize the relay even if I set the pot very close to the energize point.
  9. T

    Question about technical limitations of 12v relay switches

    Hi, I'm new here, I've just started a project that has me building an electrical circuit for the first time and I don't really know what I'm doing! I'm hoping someone can answer a quick question. I have a 12v electric motor (has two power levels, at 9A and 20A and it was suggested to go with a...
  10. Asheekay

    Hello (Introduction and some devices enquiries)

    Hi all. I am Asheekay, a man from Pakistan. I am interested in electronics and have some idea about DLD (digital logic and design), studying it in one of the semesters in the college. However, I am generally ignorant about practical electronics applications. For a start, I would like to know...
  11. A

    Upgrading Old Fuse Box

    Hi guys, I am looking for some electrical help on how to add a secondary fusebox to my car. I have a 1989 Maserati 430, these era cars came out of the factory with underpowered fuseboxes prone to over heating. Well, my box was toast when I bought the car and now that ive had the car a few months...
  12. Clarkdale44

    Relay timer 2 min on and 10 min off, and repeat constantly.

    Hello I want to make an auto relay timer circuit such that it turns on the load connected to the relay for 2 min then turns off for 10 min and repeats this cycle indefinitely. I have a few 555 timer lying around was hoping if could make something out of it. The timings doesn't needs to be...
  13. S

    Help!!!!!, Relay in motorcycle 12V environment,

    Hello, I was hoping some can help me figure if i can use SRD-12VDC-SL-C, to turn may parking light into blinkers. Here is the issue; I purchased aftermarket blinkers for my motorcycle, these only light up while blinkers are turn on, making you less visible during regular operation. Hence...
  14. H

    Please advise a device to change a pulse to on/off signal

    A EC Fan output a signal 3 pulses per revolution (Isink max = 10 mA), please advise a device to change this signal to on/off signal so that output ON when the Fan is running and OFF when the Fan is not running. Let me know a specific model would be greatly appreciated because I am green for...
  15. J

    Single pulse latching relay?

    I'm working on a project for school, it's basically a IR controlled fan with 9V DC. Basically you press any button on a tv remote and the IR sensor ( TSOP 1838) picks up the signal and outputs it to the fan and the fan spins. Problem with this is I have to continuously keep a button pressed on...
  16. H

    *Wiring temp sender to kick fan in?*

    2003 Fiesta 1.25: had problems with the fiesta overheating even though temp gauge says normal temp on dashboard. After box ticking all the usual culprits (relays, fuses, isolating fan to test it works which it does etc) found out it's the ECU ignoring any messages from the temperature sensor...
  17. sino007

    Calculating the value of the resistance for controlling the speed of AC fan

    i have a single phase ac fan that i would like to control its speed i am a bit new in this field so please bear with me i had the idea of fixing 3 speeds with 3 switches one for each speed: (25% 50% 90%), and 3 relays each switch activates a relay and each relay wired in series with a...
  18. A

    simple PV low-power relay

    Hi guys, I am new to all of this, in fact I started digging yesterday, so forgive my poor diagram :meh:. Mission: I want to built a small solar powered light arrangement, that turns on automatically after dusk. Currenctly I have battery packs (BP) hooked up to a solar pad (SP) via USB and there...
  19. L

    Simple Solid State Circuit Isolating Relay?

    I would like to replicate the action of a very low load automotive relay using solid state components. I understand simple electronic/circuit principles and what basic components do, and I can probably (probably) handle ohm's law, and I can solder, but that's about the extent of my abilities. I...
  20. CBB9

    Audio Triggered Switch Help

    I'm hoping someone here can help lead me in the right direction on an experiment of mine. In my car I have an automatic starter that includes a wire that when given the 12v negative connection will trigger the automatic starter. What I would like to do have this negative connection activated...
  21. R

    Lightning protection for signal loop

    i would like to add lightning protection to my Automower 450X. The ground loop, which consists of five wires that run around the perimeter of the property and subdivide it, has to be disconnected from the transmitter/charger if there is the threat of an electrical storm. And of course the...
  22. B

    Scary Alarm Schematic Needed

    Hi everybody. I'm new to this forum. I've got a notion to build an alarm system for the detached garage from parts I either already have or have seen online. Here are the criteria that I want my system to meet. 1) Must operate on 12volt DC Deep Cycle Battery with trickle charger. 2) Must operate...
  23. E

    USB data triggered relay

    Hi, I have a usb symbol barcode scanner that I want to trigger a 5v relay when data (barcode reads) pass through. I want to be able to intercept the information without interfering with the normal connection and operation of the scanner and without ongoing background software on the intended...
  24. D

    remote release DIY 2 way radio- solenoid

    heres my project and or idea.... im trying to use a two way radio to signal another two way radio. i have 12 VDC magnetic solenoid thats hooked to a bird launcher(big sling shot used for training retrievers). when solenoid receives power it retracts in turn releasing the latch.... i have done...
  25. Unit00

    Relay Chatter in Load Disconnection Circuit

    Hey guys. I'm designing a series pass voltage regulator with feedback. I'm trying to disconnect the load when the load current or control element temperature exceeds a value. The attached photos show my circuit design. The temperature cutoff circuit works as is, but the current cutoff does...

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