Recommendation on low voltage relay

Model Railroader Electronics and DCC
1

I am looking for an affordable low voltage relay that can be triggered by 20 mA at 5-12 volts. Does anyone have a recommendation?

2

You might try an optical isolator, I doubt if there is a relay that will pull in at 20ma. Solid state relays will but they are pricy. If you are using an Arduino look for an Arduino relay driver.

Mel

Modeling the early to mid 1950s SP in HO scale since 1951

My Model Railroad
http://melvineperry.blogspot.com/

Bakersfield, California

I’m beginning to realize that aging is not for wimps.

3

Just curious on what is limiting the current to 20ma?

Optical isolator seems to be a good solution.

Some years ago I made some circuits using reed relays that had low current requirements but those are long one. Usually the lower the current for the contacts, the lower the current is for the relay coil.

I think mine had a contact limitation of 0.5 amp and did not require much current to operate the coil.

Radio shack use to sell a relay to use with a decoder output but that one is long gone.

I was just at Mouser Electronics and they call out coil resistance and required voltage.

Rich

4

Well, if you know the coil resistance and voltage, you know hoe much current it will take. I have soome small relays that draw low enough current to work directly off an Arduino pin with no driver. The contacts also have sufficient rating for what I intended to use them for. But they are VERY tiny, smaller than an 8 pin IC. That’s what I get for not reading ALL of the data sheet. I was looking for coil voltage and current, and contact rating - these meet those requirements. These are even too small to plug in to a breadboard, to even test one I have to solder wires to it and then plug that into the breadboard. Since I was going to use a driver anyway, like a ULN2003, I’ll be looking for some physically larger relays even if they draw more current. This isn’t for anything battery powered, so I don;t need to watch the current down to the nanoamp.

–Randy

5

At Digikey, it’s very easy to set filters for the specs you want.

Here you go:

http://www.digikey.com/products/en/relays/signal-relays-up-to-2-amps/189?k=&pkeyword=&pv72=1&pv72=13&pv72=35&pv72=2&FV=a7c0001%2Ca7c0066%2Ca7c000b%2Ca7c006f%2Ca7c0075%2Ca7c0077%2Ca7c0079%2Ca7c007a%2Ca7c0080%2Ca7c0081%2Ca7c0087%2Ca7c0011%2Ca7c0014%2Ca7c0016%2Ca7c0019%2Ca7c001e%2Ca7c0020%2Ca7c0021%2Ca7c0027%2Ca7c002b%2Ca7c01ba%2Ca7c01cf%2Ca7c002f%2Ca7c01e0%2Ca7c01f1%2Ca7c01f4%2Ca7c01f5%2Ca7c01f7%2Ca7c01fb%2Ca7c020d%2Ca7c0210%2Ca7c0211%2Ca7c0221%2Ca7c0239%2Ca7c0039%2Ca7c003a%2Ca7c0266%2Ca7c026c%2Ca7c003f%2Ca7c028c%2Ca7c0046%2Ca7c004a%2Ca7c004e%2Ca7c0050%2Ca7c0052%2Ca7c0054%2Ca7c0056%2Ca7c005a%2Ca7c005c%2Ca7c005f%2Ca7c0063%2Cffe000bd&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25

6

I use 10ma 5v reed relays - http://arduinotronics.blogspot.com/2013/01/working-with-reed-relays.html

7

These seem to meet your requirements:

https://www.amazon.com/gp/product/B00KTELP3I/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

I picked up a few a while back intending to use them to control power to staging tracks with stationary decoders. My plan is to include them in routes for the staging tracks so only the selected route has power. I haven’t deployed them yet so I can’t vouch for their performance.

8

try an “Arduino Relay” from many suppliers on Amazon or eBay. These use a 5V supply and a logic level input and are available in 1,2,4,8 and 16 channel versions (each with an SPDT relay, you can parallel as needed) and run about $1.50 per segment, so the price is hard to beat.

9

Do you need latching or non latching?

The parts are quite common. Panasonic makes quite a few DPDT. Mine is non-latching and consumes about 20ma at 5 V.

10

are you using it for high voltage high current app like 120 at 10 amps ?