Car flasher issue with gadget i built  - Page 1
Forum section: electronics / beginners

author: Thedrunkenflea
author_rank: Contributor
timestamp: December 18, 2022, 01:24:32 pm
content: Hello! You guys helped me out last time and it was cool to get advice from experienced sparkies like your self.I love building gadgets even if I dont have any practical use for them. My issue is very simple i run a 12v 20amp car flasher a 3 pin one - im sending a 12v 10amp DC through it and need it to flash on and off.The trouble is its just "buzzing" and i dont know why because its in the volt and amp range. I might have meter of wire at best of 14 gauge wire running through it - the simple circuit has nothing else.Is this known as voltage kick back? I tried weaker power packs such as 12v 3amps but it does the same thing.The flasher is in working order - and works well with my other gadget i built which is a minor EMP.What could solve this issue? resistor? diode?Thank you.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 18, 2022, 01:56:41 pm
content: Quote from: Thedrunkenflea on December 18, 2022, 01:24:32 pmIf it is an "old style" flasher, used as a car turn indicator, it employs a set of contacts, which are made & released by a bimetallic strip.Initially the contacts are "made", application of DC 12volts light the lamp via the contacts & a heater winding wound around thebimetallic strip, which deforms, opening the contacts, & hence the circuit.These normally operate two 12v, 22w bulbs, so it would normally work with around 4 amps current flow, not 20 amps.Are you actually measuring 10 amps, or that is just the maximum rating of the power supply?

author: Thedrunkenflea
author_rank: Contributor
timestamp: December 18, 2022, 02:56:43 pm
content: ya one one of my gadgets has 100ft of 1.5mm copper wire with same power pack 12v 10amps.It works fine with that.I already tried a 12v 4 amps power pack and it wont work with that either.Im not sure why it wont take the load.This is the flasher:https://www.amazon.co.uk/Gebildet-Electronic-0-1W-150W-Motorcycle-Adjustable/dp/B07XRJ57C9/ref=sr_1_20?crid=3KEWO8GHXQGV2&keywords=12v+20a+amp+flasher&qid=1671375355&sprefix=12v+20aamp+flasher%2Caps%2C67&sr=8-20I also had a different 2 pin flasher and for some reason reducing the wires contact to the pins made it work. Unfortunately i don't have the ratings for it as it broke it was already pretty old and been used a lot.thanks

author: themadhippy
author_rank: Super Contributor
timestamp: December 18, 2022, 03:04:13 pm
content: forget the power pack rating,what is connected to the output of the flasher

author: Thedrunkenflea
author_rank: Contributor
timestamp: December 18, 2022, 03:07:52 pm
content: a meters worth of 14 gauge wire the ohms will be next to nothing - i think thats what your asking sorry if i didnt answer correctly.

author: themadhippy
author_rank: Super Contributor
timestamp: December 18, 2022, 05:00:09 pm
content: so your shorting the output with a bit of cable and expecting it to work with er lets see ,14 gauge is 2.5 ohm per 1000foot,1 meter of the stuff at 12 volts, around 1500 amps flowing through it,o hang on that's a meter there and a meter back so 750 amps

author: Thedrunkenflea
author_rank: Contributor
timestamp: December 18, 2022, 09:41:06 pm
content: Not really.3 pin flasher -Power pack live and returnLive goes on B+Return on E - (plus one end of the cable)L - is other end of cableComplete circuit - My other gadgets work OK with it.I said the wire im using for this device is a meter long - maybe two meters at best.

author: SmallCog
author_rank: Frequent Contributor
timestamp: December 19, 2022, 02:42:06 am
content: Is your "device" attached to the flasher just a short piece of wire from the L terminal to the E- terminal?If so add a resistor between your piece of wire and the L terminal, something around 7Ohms with a decent power rating.Actually add 2 of the cheap 20W cement/ceramic resistors in series (one after the other) between the L and your wire, something around 4Ohm will work ok. These are readily available from eBay and other marketplacesVarying this resistance will vary the speed of the flashing so it may take some fine tuning. Given that you could consider buying a bunch of lower Ohm rating resistors eg 2 Ohm and putting them in series to get the speed you desire. Probably find postage is more than the resistors.Not sure what you're trying to accomplish but I hope you have fun

author: EPAIII
author_rank: Super Contributor
timestamp: December 19, 2022, 05:27:45 am
content: OK, you have a meter of wire on the output of the flasher. ButWhat is on the OTHER end of that wire?Is it just an open circuit?orIs there one or more light bulbs?orIs there something else connected as a LOAD?Auto flashers MUST HAVE a LOAD that consumes a certain amount of current. If that current is not flowing THROUGH something, then the flasher will do NOTHING or just buzz as you describe.

author: Thedrunkenflea
author_rank: Contributor
timestamp: December 19, 2022, 08:18:18 am
content: Quote from: EPAIII on December 19, 2022, 05:27:45 amThis is exactly my problem - it makes sense.As far as I know it is an open circuit - no bulbs - nothing connected to the load - my larger coils must be using more current hence they work.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 19, 2022, 08:48:36 am
content: Quote from: Thedrunkenflea on December 19, 2022, 08:18:18 amClassic flashers would flash faster, if they lost one of the front/rear pair of lights.This was an important safety feature, as it let the driver know one lamp was out of service.The first generation of solid state flashers couldn't do this, as implementation of that function was difficult, but later versions could.It is possible that your flasher has a special circuit (or program) devoted to reproducing such behaviour, & they never anticipated anyone would run it with no load, so the "buzz" just happens to be that system trying its best to deal with a situation it was never meant to handle.

author: Thedrunkenflea
author_rank: Contributor
timestamp: December 19, 2022, 08:52:20 am
content: Ya some flashers work with my set up but they are "old style" it looks like ill have to build a custom power pack. I was hoping id maybe need a few parts and just solder them up.thanks man

author: Thedrunkenflea
author_rank: Contributor
timestamp: December 19, 2022, 08:54:00 am
content: Quote from: SmallCog on December 19, 2022, 02:42:06 amAh thanks i didnt notice this post - resistors might be the key and thank you for telling me where to attach it too!i can try this.

author: Thedrunkenflea
author_rank: Contributor
timestamp: December 19, 2022, 12:43:18 pm
content: A 5 watt resistor worked it started flashing - but i wasnt getting enough flow to charge up my coil.I might have to reduce main wire to a smaller gauge. It also got too hot. If i up the resistor rating then it probably wont allow enough power through with that.