old rotary switch - Page 1
Forum section: electronics / beginners

author: m3vuv
author_rank: Super Contributor
timestamp: February 17, 2022, 11:56:29 am
content: Hi all i have an old rotary switch from a motorola gp340 ht,its 16 position but only has 6 conections on the rear of it,any ideas how it is wired?

author: m3vuv
author_rank: Super Contributor
timestamp: February 17, 2022, 12:03:10 pm
content: Let me make the question more clear if i can,the switch originaly was used to select each of the 16 channels on the radio,how can it do that with only 6 connections on it?,just wondered what electrickery is beeing used here ?.Tia

author: themadhippy
author_rank: Super Contributor
timestamp: February 17, 2022, 12:06:31 pm
content: meter it out,my guess its something to do with binary

author: Ian.M
author_rank: Super Contributor
timestamp: February 17, 2022, 12:14:28 pm
content: Agreed.What's the betting its 4 bits to a common (either Grey code or binary), possibly plus a 'push to click' contact sharing the same common?@m3vuv: When you are asking us to be crystal ball gazers, a photo of the actual part in question would be nice!

author: m3vuv
author_rank: Super Contributor
timestamp: February 17, 2022, 12:54:06 pm
content: heres a pic of the rear of it.theres 4 pins on each side not 6 in total,need better glasses!

author: m3vuv
author_rank: Super Contributor
timestamp: February 17, 2022, 01:05:36 pm
content: sorry,i just noticed there are in fact 3 wires per side in a row,not 8.,i am just soldering some tails on them to bell them out.

author: Ian.M
author_rank: Super Contributor
timestamp: February 17, 2022, 01:11:24 pm
content: Quote from: m3vuv on February 17, 2022, 12:54:06 pmQuote from: m3vuv on February 17, 2022, 01:05:36 pmYes, you do need better glasses!Maybe get a bench magnifier as well?Also, taking good photos for the forum requires some care and thought. It often helps to use a sheet of white paper behind/under the object to avoid a cluttered background and if your camera/phone has it, select closeup/macro mode. Make sure the object (or at least its most critical features) is in focus, and well lit!There's no need to solder wires to it just to 'beep' it out. You simply need to make up extension leads for your meter probes with small test clips on the ends. The female contacts from 'Molex' style 5.25" drive power connectors are a good fit on many meter probes, and can simply be covered with heatshrink for insulation and mechanical strength. Test clips that directly attach to the probes are less useful for very small pins due to the leverage they exert on the pin.OTOH if your next step is to get it hooked up to LEDs or maybe an Arduino or similar, you might as well solder the wires *before* figuring out the contacts.

author: Benta
author_rank: Super Contributor
timestamp: February 17, 2022, 05:29:03 pm
content: The Motorola radios of those days usually had an MC4044-based PLL synthesizer for the LO.Very likely that the channel switch controlled the feedback counter with a binary output, either directly or (more likely) through a PROM with counter programming patterns.

author: m3vuv
author_rank: Super Contributor
timestamp: February 17, 2022, 08:22:24 pm
content: The basic idea was for making the panell les cluttered on a si 7435 based radio kit i am building at present it had 6x pushbuttons to pull various pins of an arduino nano to ground for volume mode bandwith etc,the idea is to have a 6 position rotary switch in series with a push button to ground so turn the rotary selector to whatever you want to alter then just hit the pushbutton.,the main reason beeing by the time i have a speaker and batterys fitted there wont be a lot of room,idealy i want it pocket sized.

author: Ian.M
author_rank: Super Contributor
timestamp: February 17, 2022, 09:39:34 pm
content: Edge mounted tactile switches + rocker buttons would make far more sense. If you need a 'wheel' type control, consider an edge mounted thumbwheel.Another approach would be to use a PCB for the panel with capacitive touch buttons and sliders.In all cases, if its got to be pocketable, use a real slider power switch, preferably on the top short edge, (or face near the edge), and have three positions - off, on, on with buttons disabled.

author: Terry Bites
author_rank: Super Contributor
timestamp: February 17, 2022, 11:57:30 pm
content: https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwj5xPil9of2AhUGhlwKHcUwBjIQFnoECA8QAQ&url=http%3A%2F%2Fwww.radiotronics.co.uk%2Fpdf%2Fmotorola%2Fgp340-series%2Fmotorola-gp340-gp640-service-manual.pdf&usg=AOvVaw39XK2NnYb2hFBs9dSnnmn6