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Testing relays?? — Parallax Forums

Testing relays??

"Steamboat Ed" Haas"Steamboat Ed" Haas Posts: 29
edited 2005-05-23 18:35 in BASIC Stamp
--Hiya; I'm using the Opto 22 relay board and BS2. I've written a simple program that should be turning a relay on and off at one second intervals. To test that the relay is working I'm using·my voltmeter's beeping·continuity tester, but to date I've not made a "contact". Any ideas what might be going on? I notice that the little LED on the relay I'm testing is blinking in time with the program, but there doesn't seem to be anything else going on..

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-04-14 15:03
    Ed,

    ·· If you're using SSRs, you won't get continuity that way.·· These devices are specifically design to switch a load (Usually AC) using solid state components.· In the case of the AC version, by switching during the AC signal's zero-crossing point.· You will simply have to switch the appropriate load to test them.



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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • "Steamboat Ed" Haas"Steamboat Ed" Haas Posts: 29
    edited 2005-04-14 15:18
    ···· --Actually I was testing the DC relay at the time, but if it behaves the same way I'll keep that in mind; thanks!
    ···· --Ya know, it would be neat if Parallax offered a relay with a transparent case, so one could observe the internal workings in action..

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    ························ Hacking the Trailing Edge!
    ················http://www.nmpproducts.com/intro.htm
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  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-04-14 15:29
    Ed,

    ·· If the DC Relay is an Opto 22 SSR, then even a clear case won't help you as these are not mechanical relays.· Inside is solid state circuitry controlled by an optically coupled interface, consisting of an LED (sealed) and a photo-transistor type interface, along with power control circuitry, although this varies since no manufacturer wants you to know exactly how theirs works.· But the block diagram is the equivalent.

    ·· Basically if you can hear the relay click when it activates, then it's probably mechanical, and you should be able to test for continuity.· If not, try measuring resistance instead, and you should see it drop (Even on the SSR).

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • "Steamboat Ed" Haas"Steamboat Ed" Haas Posts: 29
    edited 2005-05-12 02:09
    ···· --Oops, right you are. Finally got everything set to rights when I connected wires from the posts on the upper right corner of the "daughter" board to the posts on the upper left of the relay board. But when I showed this·to a pal of mine he said that, although this works to get power to the relays, it's a bad way to do things and that I should use an external power supply to do this. Not sure why; no expert me.

    ···· --Also finally got voltmeter readings when I reversed the probes, so I can verify that the relays are, indeed, working.

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    ························ Hacking the Trailing Edge!
    ················http://www.nmpproducts.com/intro.htm
    ················---Decks a-wash in a sea of words---
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-05-12 17:52
    Ed,

    ·· I'm glad you finally got that figured out, but if you could explain exactly what you're trying to do, what you want to connect, and what loads you're trying to drive, maybe a better solution could be suggested.



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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • "Steamboat Ed" Haas"Steamboat Ed" Haas Posts: 29
    edited 2005-05-23 18:35
    ·· --I'm building an art car; on the cheap, natch, but with a fair number of features. I'm using the relays to switch multiple strands of EL wire from www.coolneon.com. All power will come from a 12-v battery and from there it will be split into various voltages for different tasks, using a pile of those in-dash cigarette-lighter type Radio Shack transformers. I'll hook each transformer to its own relay, as various configurations of EL wire are· needed. More details of what I'm planning can be seen here: www.nmpproducts.com/artcar.htm

    ··· --I've got it all working on the testbench; the next goal will be to get it sorted out on the vehicle in such a way that it's weatherproof and the cable routing is not going to get whacked and broken. Never the tidy person, me, I see many zipties in my future! yeah.gif

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    ························ Hacking the Trailing Edge!
    ················http://www.nmpproducts.com/intro.htm
    ················---Decks a-wash in a sea of words---
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