Salvaging a low voltage/amp solenoid switch?

[LI-ghtcycle]

Heya all, I'd hate to have to source one from the local hobby shop or radio shack if I can salvage one from some common consumer electronics or old radio equipment laying around the house.

I need a solenoid switch to run 12V 3A to power my MS Headlight, so not a big one, but I thought with all the old stuff my father has collected there might be something pretty common that would have such a switch in it.

Thanks!

 

[amberwolf]

Do you mean a relay? (contactor)

If so, many small UPS have them, typically rated for coil voltage of whatever the battery voltage is in them. Small ones are 12V, server types 24V and 48V and up. Can be 2A thru 20A+ for contact ratings, depending on the power rating of the UPS.

5V coil relays are sometimes found in old CRT monitors, but they usually are much lower contact ratings, for AC, used for degaussing the CRT.

 

[LI-ghtcycle]

Ok, yes I believe I am just used to what they are called in a automotive terms, man I think I got rid of a old UPS about a year ago, oh well, how easy do you think one of these could be identified in an old CRT? Dad never throws anything away, so we have everything from vacuum tube radios to some of the first home computers TRS80, Commodore 64. I know of at least 3 CRT's lying around.

I'd love to have a good reason to salvage some of this stuff and get rid of what's not needed. :wink:

 

[An average human]

washing machines are filled with 5 amp relays, i have recently taken two apart and got hold of 5 each , i think that microwaves, dishwashers and similar also may have relays of some kind. hope this helps.

 

[LI-ghtcycle]

Good ideas, thanks!

I have at the moment just an 90's CRT Computer Monitor and 80's era small TV, which would be the best to look inside for a relay?

I wish I had either a washing machine or microwave to look inside, but don't have one yet but I could goto goodwill and look for one if I will have a better chance getting one there.

I suppose it will be a large black box on the PCB? Or will i generally look like a transformer with an exposed coil?

 

[amberwolf]

In the monitor it'll probably be a sugar-cube sized box, could be any color including transparent/translucent. If you post a good closeup of the whole PCB I can repost a version with the relay circled, if it has one.

If you are salvaging parts off of PCBs that you do not care about the condition of the PCB, desoldering them with a small palm-sized butane torch works very well and is less likely to damage the parts than a soldering station/etc probably would be, depending on your experience. Just pass the torch set to lowest over the area in circles with the flame tip not touching the PCB, tapping the PCB on the table, and bigger stuff just falls out.

Parts like resistors that usually have their wires wrapped under the PCB typically require pulling out with needlenose while heating PCB, so you have to put the PCB in a vice to leave hands free for the torch and pliers. (or put the torch in the vice so you don't knock it over while manipulating the PCB and pliers)

 

[LI-ghtcycle]

Great Thanks AW, I'll post a pic here soon, just to make sure I understand then, you think I have a better chance finding a relay in the Monitor than the TV set then?

Also, I won't need nearly as large a relay as I originally thought, my DC to DC only puts out 2.5A at 12V ... I wonder if the same Cordless Phone might have one too on it's PCB (the one that I took 18G wire plugs from) I'll post that too ... I already took off the female power connector that fits the male connector from the Magic Shine perfectly! 8)

Pics to follow soon!

 

[amberwolf]

you think I have a better chance finding a relay in the Monitor than the TV set then?

They probably both have one, but there are some that use a type of thermistor (NTC, I think, but not sure) to trigger the degaussing instead of a relay. The ones that allow you to degauss from an on screen menu almost certainly use a relay.

Also, I won't need nearly as large a relay as I originally thought, my DC to DC only puts out 2.5A at 12V

Maybe it only puts out that much; but how much does your light draw, the one you are switching on and off? You only need a relay big enough to switch the actual load.

... I wonder if the same Cordless Phone might have one too on it's PCB (the one that I took 18G wire plugs from) I'll post that too

I doubt the phone has any relays in it.

 

[LI-ghtcycle]

Eureka!

I found and removed this 5A relay (gotta love IBM over-engineering ... thanks again for the tips guys!), and it even has 2 sets of contacts, now I can have a second gizmo activated with the headlight, I'm thinking a Sonic Weapon charging switch! No, really officer, it's just a REALLY loud horn

And if it has a 20 hour continuous use on regular batteries, I think my E-Bike battery should keep it going as long as I like :lol:

(I HOPE it comes with ear plugs :wink: )

http://www.gadgettastic.com/2008/03/13/sonic-weapon/

 

[LI-ghtcycle]

Ok, now I have a NEW problem, the relay won't open at the 3.3V lower power supply, and I'm pretty sure I'm ok using the 12V supply since the low voltage side of the relay won't draw what the MS headlight will draw, but before I let out more magic smoke, I wana see if anyone here can tell me if I'm asking for trouble putting 12V through a 18G wire switch. :?

Thanks!

 

[amberwolf]

Is the coil voltage on the relay 12V? That's what it looks like it should be based on it's markings. If so, then that's what you use to turn the coil on, and switch the relay from open to closed.

 

[LI-ghtcycle]

I have no idea, it came out of a IBM computer monitor, so if you can tell me from the writing on the side of the relay, let me know.

I tested it first to see if it worked with a 9V battery I had laying around that was warn-out and it only worked once I used a newer 9V battery that had 8V left, so I know that it takes more than 3.3, but less than 9V to turn it on for sure, anything else is just a guess. :wink:

 

[GrayKard]

I have no idea, it came out of a IBM computer monitor, so if you can tell me from the writing on the side of the relay, let me know.

I tested it first to see if it worked with a 9V battery I had laying around that was warn-out and it only worked once I used a newer 9V battery that had 8V left, so I know that it takes more than 3.3, but less than 9V to turn it on for sure, anything else is just a guess. :wink:

Well, where it says 12VDC then some space and a C. Looks like 12 volt and the C for coil. That's what I would assume if I had it and I would try it with 12 volts and see if it gets hot when left on for a while.

Sure you could let out the smoke, but that's half the fun. :wink:

Gary

 

[LI-ghtcycle]

Well, where it says 12VDC then some space and a C. Looks like 12 volt and the C for coil. That's what I would assume if I had it and I would try it with 12 volts and see if it gets hot when left on for a while.

Sure you could let out the smoke, but that's half the fun. :wink:

Gary

Oh wow now I have PROOF that I am blind! :lol:

Thank you! How I managed to miss that 12VDC is beyond me, I guess I have the answer now.

 

[LI-ghtcycle]

Well, I haven't got it all buttoned up yet, but the relay is plenty happy at 12V!

I wanted to show off my lucky find too when I realized that the female connector from the same cordless phone I took the battery connectors from fits the Magic Shine plug perfectly! Just had to trim the plastic housing down and shrink wrap it and solder it up (still crappy pic, but better than most of mine )

I tested out each component before soldering good thing too! For a bit I thought I had miss-labeled my blinker wires, but no I just Wired in the L blinker lead to the R one, so I fixed that and everything works!

My neighbor had another of those scooter thumb switch clusters, so I could salvage a good one out of the 2 (the blinker switch managed to die, maybe I had something to do with that ) but it worked out great, since I was forced to solder in a new switch, I could now use the color coding I wanted for each wire. (i.e. black for common, red for R blinker etc.)

 

[GrayKard]

Nice. Glad to see it worked out and is already done. I love when I can reuse something and it works better than buying new.

I bought a couple of relays off Ebay but it turns out one of the legs is for a lower voltage control circuit so they won't work for my star/delta conversion. But I found some parts salvaged from 35mm projector power supplies at work and in the bags were two perfect 3pDt relays. 60 volt dc coils on them so I can just hook them straight up to full pack voltage too.

I have lots of other used but good parts at work that are useless now as we have switched to digital. So some of them will end up on my Ebikes now and then. :wink:

Gary

 

[amberwolf]

Cool that it worked so easy. I love techological synchronicity.

I am about to build a "dashboard" for DayGlo Avenger, as an experiment prior to doing so for CrazyBike2. I've been considering it at least since I saw yours.

 

[LI-ghtcycle]

I can't take the credit there, DoctorBass gave me the idea, I just added my own touches.

But, thanks I'm really glad how it's working out too, tomorrow I should be able to button it all up and take pics of the final product. 8)