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  1. J

    Measuring current draw from permanent +12v

    My car has a power folding mirrors which currently have a Ignition/ACC controlled +12v being the main +12v source for folding and unfolding. Problem is that when ignition is turned off I cannot operate the folding function as the +12v from IGN is interupted. So what I am thinking to do is take a...
  2. J

    Operating mirror folding motors

    I have the following circuit diagram from my car which basically operates the mirror folding motors when I press a switch. If switch is pressed in, the mirror stays folded and if the switch is released then the motor unfolds. I'm trying to operate the mirrors directly without the switch. Can...
  3. J

    Reducing voltage for a driver driven LED strip

    I have the following glow strip wire which comes with a 12V driver that you plug directly into a 12v source from the car. However, directly plugged in the drivers makes a humming sound and I dont want to hear this at all. I did a bench test with a variable voltage PSU and I much prefer the light...
  4. J

    2 relays with a shared common

    I've got the following relay design where I've got two relays sharing the same common directly from +12v of a car battery. The relay coil is powered by two different circuits. In most cases only Power Source 1 or Power Source 2 will be on. However, there will be occasions where power source 2...
  5. J

    Door Bell Chime Transformers - UK

    I have a hard wired door bell chime. It's been running for about 10-11 years since it was installed in my new-build house. I removed the cover to inspect the transformer and the transformer is rather hot. I've been inspecting it for a few weeks now and it's always hot. Not hot that it will burn...
  6. J

    Powering device with Cat5e data cable

    I need to run 12v DC power through a cat5e cable. Does anyone know the maximum amps a single cable can carry? There are total of 8. I'm using 2 for door bell and I need to use the cat5e if possible so that I don't need to externally run a new cable. So I have 6 spare. It one isn't good enough...
  7. J

    Help measuring resistance of fuse with this multimeter

    I have a rather old multimeter. I've attached a photo. I am diagnosing an issue with my car. The user guide says to remove the fuse and measure resistance between the terminals and it asks: Is the resistance vale 1 Ω ± 1 Ω? Can anyone kindly guide me through how I can use my multimeter to...
  8. J

    Combining 2 +12v wires in the car

    I need to power an LED in the car from two power sources. One is from the IGN which activates when ignition is on and another is from a puddle light source which activates when you are near the car. Only problem is the puddle light stays on for a few seconds even after the ignition is turned on...
  9. J

    Programmable Microcontroller with relays

    I'm completely new to programmable microcontrollers. I am looking for a solution. I would like some sort of device that is always on and powered with 12v power source. The device also then has a completely standalone additional 12v trigger from a completely different power source. When power is...
  10. J

    Mixing optical sound cable with 3.5mm cable

    Does anyone know if there is a way to mix a 3.5mm audio line into a optical sound line? I have a sound bar and from my TV I have connected a optical cable to the soundbar. However, I have a Amazon Echo Dot which i would like to connect to the same speaker. Although the sound bar has another...
  11. J

    Combining 2 audio outputs into 1

    I have 3.5mm audio outputs from two different devices. One is a TV and the other is amazon echo dot. I need to connect them to my sound system on the same 3.5mm input channel. Now from what I have read it is not safe to use audio splitters for this purpose as the output of the two devices might...
  12. J

    Turning LG smart tv off on the mains

    I want to connect my LG smart TV to a samsung smartthings smart power socket so that I can turn the tv on and off with the app and voice command. Question is, is it safe to just turn a tv off at the mains without putting it into standby first?
  13. J

    Relay to turn off power instead of on.

    I have a 12v supply coming from the cigarette/accessory socket from my car going to some LED lights. This turns on as soon as my car is turned on. However, I want this 12V source to turn off when my sidelight +12v line becomes live. I was thinking of a relay but that wouldn't work because a...
  14. J

    Solar Panel and 12V Deep Cycle Battery advice

    I have a 12v 100Ah deep cycle battery which will be connected to a 10A 12V Photocell Switch that will power about 10x 1w LED lights in the garden at night. To keep the batteries topped up I have a small limited space on top of a pergola that I want to place 2x 20W monocrystalline solar panels...
  15. J

    Micro USB port pin configuration

    I have a damaged Micro USB port on my Android Tablet which I would like to remove and then I would like to cut the micro USB connector of from a OTG cable and directly solder it to the board. However, I need some help because i've cut a few spare USB cables and they all have 4 wires inside...
  16. J

    Help calculate power usage

    Can anyone kindly help me calculate power consumption based on the following: If I have a 5v 3950mAh battery powering a Tablet, and over a 24hr period i lose 4% battery. I am going to be replacing this battery and run directly from a 12V car battery using a 12v to 5V converter. What would the...
  17. J

    USB power for tablet and a USB hub

    I have the following USB configuration which takes +12v from the car which goes through a converter to reduce to 5V. It seems to work fine without any problems. But my only concern the part where the same power from the converter goes as an external power source to the USB hub. So technically...
  18. J

    reducing 5V to 4v or 4.2v MAX

    I have a 12v to 5V 3A convertor. What would be the best way to further reduce it by at least 0.75V? I was thinking of a resistor but that will be generating a lot of heat. Is there a better way to reduce the voltage and have it stable? The current draw will vary. In most cases it probably won't...
  19. J

    12v relay with time delay and reverse polarity

    Looking for some help in wiring up a 12v relay for my car. Basically, I have a 12V relay that is activated with my windscreen washer circuit. So when the washer pump is active, the relay activates. Problem is that the relay only stays active for the period of time that I hold the washer stalk...
  20. J

    Li-Polymer with i2c chip

    I have a Google Nexus tablet which has a 3.8V Li-Polymer. I want to remove the battery completely and run the tablet directly on a step down converter running at 3.8V. I've tested the theory and the tablet works fine. Only problem is that the Li-Polymer battery of the tablet has 2 additional...
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