Help with reproduction car timing relay - Page 1
Forum section: electronics / general

author: edb1984
author_rank: Contributor
timestamp: January 08, 2021, 08:51:58 pm
content: HelloI need some advice, hope someone can help.I want to find someone to help me draw up the board below that I will post pictures of, and also ideally provide a list of parts so that I can make a few of these for myself and friends in my car group - not loads, maybe 20.I was planning on getting someone to copy this design then send over a file that I could then print and etch my own PCB myself (I have done before) then I can order the components online and solder up myself.BUT then a friend at work was saying I could probably ask someone to design it then order the PCB ready made online and get it posted to my door?I don't expect someone to do this for free so I am happy to cross someone's palm with silver if they could do this for me for a reasonable price.So, I suppose my basic question is - where would I go to get something like this done? And what could I except to pay?

author: edb1984
author_rank: Contributor
timestamp: January 08, 2021, 08:59:02 pm
content: here are some photos of it - i can get more detailed photos and dimensions if needed

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 08, 2021, 09:22:54 pm
content: Is this some kind of special relay that can't be replaced?

author: Mangozac
author_rank: Frequent Contributor
timestamp: January 09, 2021, 01:32:13 am
content: Quote from: S. Petrukhin on January 08, 2021, 09:22:54 pmLooks like some kind of timer/relay module.Be prepared to pay a lot to get a professional to do it. You will want to hope to find a hobbyist that will do it on the cheap.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 09, 2021, 03:10:20 pm
content: Quote from: Mangozac on January 09, 2021, 01:32:13 amI think it will be difficult to find a person who will do this from photos, if only because of finding out the size and position of the contacts. You will probably need to send a sample.edb1984, if you are ready to send a sample to Russia, I can probably help you.

author: CJay
author_rank: Super Contributor
timestamp: January 09, 2021, 03:18:24 pm
content: It would be useful to let us know which vehicle it's from and what it's used for.If it's a safety critical part like fuel pump relay for instance I wouldn't touch it with a barge pole, if it's a windscreen wiper delay or something similarly non safety related then maybe I'd be interested in helping

author: Rat_Patrol
author_rank: Frequent Contributor
timestamp: January 11, 2021, 12:51:58 am
content: The IC is obsolete, but compatible parts I'm sure exist. I didn't look that far.The board is stupid simple, as is the schematic; single layer boards are easy.The BOM will be the hardest part, and then it may need to be modified slightly (and also possibly the schematic) to accommodate new production parts. Most of the parts look shelf, but identifying the diodes would be about the worst of it.What exactly does it do? This may be a job for a re-design with a 555.

author: phil from seattle
author_rank: Super Contributor
timestamp: January 11, 2021, 04:41:23 am
content: Quote from: Rat_Patrol on January 11, 2021, 12:51:58 amFrankly, I bet it could be done with an Arduino Nano and a few mosfets. Looks about the right size. With the right programming, it could be end user tweakable - hook it up to a PC and tweak the timing or what ever.

author: floobydust
author_rank: Super Contributor
timestamp: January 11, 2021, 07:59:33 am
content: I sketched the schematic and it uses at least five different diodes which makes it a bit harder to reverse engineer. D1 is really weird.Kind of a strange circuit, it has two or three time delays and is powered from one input "16" and triggered from the others.

author: SMTech
author_rank: Frequent Contributor
timestamp: January 11, 2021, 08:43:30 am
content: Quote from: phil from seattle on January 11, 2021, 04:41:23 amWell that's true of many small circuits of this age, a surprising number of things were controlled with 555s and some logic, we even still get asked to build things that way sometimes. The IC in this instance tho' is only obsolete if you insist on putting MC at the beginning and that has been true for years.

author: TomS_
author_rank: Frequent Contributor
timestamp: January 11, 2021, 10:53:35 am
content: Would MC14538 just happen to be Motorola numbering for something like a CMOS 4538? Both part numbers are multivibrators, but do have slightly different pinouts it would seem.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 11, 2021, 01:29:15 pm
content: Quote from: floobydust on January 11, 2021, 07:59:33 amI can assume that this is a turn signal relay and it changes the flashing frequency when the light bulb burns out, measuring the load current.

author: Rat_Patrol
author_rank: Frequent Contributor
timestamp: January 11, 2021, 04:55:01 pm
content: Quote from: S. Petrukhin on January 11, 2021, 01:29:15 pmIf so, that is a very simple Arduino job.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 11, 2021, 06:01:40 pm
content: Quote from: Rat_Patrol on January 11, 2021, 04:55:01 pmThis is a very simple operation for a pair of transistors.

author: floobydust
author_rank: Super Contributor
timestamp: January 11, 2021, 08:21:11 pm
content: Input has big 68k R2 and 4k7 R3 to GND, so I think the ignition coil must connect there.The circuit is likely a shift lamp or something. There is some kind of lamp burn-out detect below about 1A it changes to a long delay but you'd never know if the lamp is out in the first place?OP would have to give us more information to go on. It seems a bit weird still.-You can repair the module - the IC is well protected and not easy to damage. With age I would expect the two capacitors to fail C1, C3 tantalum.-You can duplicate the module with new SMT parts, the IC is available in SOIC-16.-You can redo the module (board) with new technology, a small MCU would work fine giving much fewer parts and lower cost.

author: jbeng
author_rank: Regular Contributor
timestamp: January 12, 2021, 12:31:07 am
content: Quote from: Rat_Patrol on January 11, 2021, 12:51:58 amThe part from Motorola may be obsolete, but then they haven't made parts for years (decades, actually) under the Motorola name. Texas Instruments still makes it, CD14538BE and Digi-Key shows they have 3,645 in stock at $0.53 ea. Mouser shows 12,609 in stock at $0.52 ea.

author: stevelup
author_rank: Regular Contributor
timestamp: January 22, 2021, 04:57:46 pm
content: Do you know the exact functionality of the part? It would be far easier to recreate an equivalent than religiously clone the original.

author: phil from seattle
author_rank: Super Contributor
timestamp: January 23, 2021, 01:59:59 am
content: Quote from: stevelup on January 22, 2021, 04:57:46 pmI think the original poster has given up. A drive-by posting?