Signal relays

[ruffrecords]

For a long time I have switched mic/line, phase, pad and phantom signals directly on toggles. Now with much smaller front panels my plan is to simplify by moving all the switching to relays on the main board where the mic/line signals enter and just use toggles on the front panel to switch dc to the relays.

So the current prototype PCB has for relays on it. I used this 10 pin DIP type:

https://uk.farnell.com/panasonic-electric-works/tq2-12vdc/relay-signal-dpdt-30vdc-1a/dp/1200949

With all the relays unenergised the mic input goes unaltered to the mic input transformer. So then I decide to activate the 20dB pad relay and check the pad is switched in circuit. Turns out it isn't. After lots of investigation, checking PCB layout and bench testing of individual relays, it turns out the relays don't toggle (not at 12V anyway). I have bought some signal relays years ago an finally managed to find an EA2-12NU by NEC I bought in 2011. Bench tested this and the click as the relay operates is much louder than the Panasonic ones and continuity checks prove it is operating. At the moment I am inclined to ditch the Panasonic ones (and return them to Farnell) and use something else. Unfortunately the exact NEC type is no longer manufactured but others, like KEMET, seem to still produce them.

A quick search here turned up a very old thread on this topic but none of the parts mentioned there seem to be available any more. So what is the best signal relay available for pro audio today?

Cheers

Ian

 

[[silent:arts]]

I use the TQ2 with no problems in my 51X and 500 series modules, no problems so far.
They somehow have a polarization, maybe this is your problem?
(mount them on the other side of the PCB and try if they work that way).

 

[Bo Deadly]

I find that very strange. I have used dozens of TQ2-5 in multiple projects and I have never even heard of them not working. I thought the TQ series specifically where known to work very well. Maybe they were damaged when your where testing? What is the coil resistance? What is your driver circuit? Maybe there's a little too much series resistance somewhere and you're not really getting all 12V across it? Something else has to be wrong.

 

[Brian Roth]

TQ2 relays have polarity sensitive coils.  Wrong DC polarity, they won't activate.

Bri

 

[ruffrecords]

TQ2 relays have polarity sensitive coils.  Wrong DC polarity, they won't activate.

Bri

What, even the unpolarized ones??

Well I am b------d. Brian id 100% right. Simply swapping the supply leads to these relays fixed it. I am SO pleased, I was beginning to tear my hair out. Thanks a million Brian.

Cheers

Ian

 

[JohnRoberts]

Might have a diode in series so that they can work with AC or DC.  It would take 4 diodes inside to ignore DC polarity.  :'(

JR

 

[ruffrecords]

Might have a diode in series so that they can work with AC or DC.  It would take 4 diodes inside to ignore DC polarity.  :'(

JR

I wondered that but my component tester shows the coils as just over 1000 ohms and about 400mH of inductance. You can definitely hear the relay click with the wrong polarity but with correct polarity it is noticeably louder.

Cheers

Ian

 

[JohnRoberts]

I wondered that but my component tester shows the coils as just over 1000 ohms and about 400mH of inductance. You can definitely hear the relay click with the wrong polarity but with correct polarity it is noticeably louder.

Cheers

Ian

ignore me... posting without my brain fully in gear.

solenoids create a magnet flux based on the direction of current flow through the windings (right hand rule)..

In one polarity it should pull the relay switch contact closed, in other push it away.

JR

 

[moamps]

IMO, It is just polarized relay, (a small permanent magnet is installed inside).
https://www.ia.omron.com/data_pdf/guide/36/generalrelay_tg_e_3_1_3-4%28classifications%29.pdf

 

[moamps]

What, even the unpolarized ones??

Well I am b------d. Brian id 100% right. Simply swapping the supply leads to these relays fixed it. I am SO pleased, I was beginning to tear my hair out. Thanks a million Brian.

Cheers

Ian

Is [silent:arts] on your ignore list  ?

 

[Brian Roth]

Is [silent:arts] on your ignore list  ?

Hehehe.....yes, in reply #1 in this thread, [silent:arts] posted the diagram of the relay which shows the coil polarity.

Those are good relays.  I first ran across then in the huge Amek 9098 recording desks ("by Rupert Neve the designer" as their  literature said) with maybe 15 or 20 relays per channel.  I've used TQ2 versions for a few misc. projects and noticed the coil polarity markings in the Panasonic lit.  I experimented and sure enough, Panasonic was correct.

Bri

 

[ruffrecords]

Is [silent:arts] on your ignore list  ?

No  I had alreayd perused the data sheet in detail. It has three diagrams showing two types of polarised and one unpolarised relay. They are identical so I simply thought it was a leftover from the polarised types - typical of the minor inconsistencies you see in data sheets. In fact, the data sheet does not mention coil polarity but it does mention coil direction which I took to mention the direction of current flow in polarised types.

Cheers

Ian