DPDT Single-Coil Latching Relays

[smallbearelec]

I would like to stock something like the NEC EA2 that has been recommended here, but the only coil voltages available are 5 Volts and 12 volts. Are a lot of people using the 5 Volt version? If so, powering it by dropping the 9 Volts with a regulator? Or is there a popular part with a 9 Volt coil that I don't know about and should be looking at?

[R.G.]

NEC's design data says that a 9V version exists. Do they really not make them except by huge special order?

[xshredx]

You only consider NEC?   Or are you willing to also consider Omron and Takamisawa (Fujitsu)?

Until now I use 5V relays most of the time (with a regulator), but I'm considering 9V... less current draw is a good thing...

[The Tone God]

Panasonic makes some good telecom relays too. Well priced and many come in 3, 5, 9, and 12v versions.

I actually try to use lower voltage relays. Even a weak battery is capable of delivering the amount of current needed for the length of the latch pulse in a lower voltage relay.

Andrew

[R.G.]

The amount of energy needed to cause a latching relay to flip is a constant for the magnet strengths and mechanics involved. Lower voltages need more current and more charge to cause a flip.

[brett]

Hi
at my work we use a lot of relays for hands free monitoring.

Many of the garden-variety relays seem to work on wide ranges of voltage.  The little 12V ones we buy seem to work well anywhere from 8V to 15V. 
This is one such example.
http://search.dse.com.au/search?w=9V+relay&sessionid=499ce20c11e91f902740c0a87e0106db&ts=new

cheers

[brett]

Because the resistance is often 50 to 75 ohms on 5V mini relays, you could always step 9V down to around 5V across the coil with a 47 ohm resistor in series.
Unscientific, bad engineering, dirt stupid approach.  But it'll work. 

[smallbearelec]

NEC's design data says that a 9V version exists. Do they really not make them except by huge special order?

Mouser does not list the 9 Volt version. I can ask there what the MOQ would be. Digikey offers a bunch of possibilities, mostly not stocked, but a lot with MOQ of only 50 pieces. That would work for me. For example, Panasonic TQ2-L-9V. Would someone who knows more than I do look at the specs and make sure I'm not not missing something that would disqualify it? For that matter, I searched under Relays and filtered to get the ones that met our spec. Maybe someone can suggest a best/cheapest choice?

Thanks for looking at this!

[The Tone God]

Mouser does not list the 9 Volt version. I can ask there what the MOQ would be. Digikey offers a bunch of possibilities, mostly not stocked, but a lot with MOQ of only 50 pieces. That would work for me. For example, Panasonic TQ2-L-9V. Would someone who knows more than I do look at the specs and make sure I'm not not missing something that would disqualify it? For that matter, I searched under Relays and filtered to get the ones that met our spec. Maybe someone can suggest a best/cheapest choice?

I am a fan of the TQ2 series and another. I think it was the ASX series but I haven't used them since Panasonic bought the original company so I don't know if they are still stocked. Omron has a few also that can work but they are a bit more money then the Panasonics and some need alittle more current. The TQ2s are my preference. Nice size, light, a fairly standard hole pattern (so it can fit perf boards), come in many versions of voltages and coil configurations, cheap, and some of the, if not, lowest current needs.

I never really understood people using 9v relays in battery effects. Its fine for line powered systems but with batteries most effects will still be operational long after the minimum voltage required to operate a 9v relay has passed. Kind of wasteful. I have found that most effect circuits die before the typical 9v battery runs out of enough current to still be able to energize a relay coil at lower voltages. It does require extra parts and designing but it allows you to stretch out the life of the battery. I've been doing it for many years.

Andrew

[smallbearelec]

Thanks for the replies! The 5-Volt versions of the EA2 and the TQ2 are stock items and the prices are comparable. I have asked Mouser and Digikey to get real lead times from the manufacturers for the 9-volt versions. When I have thise, I will order accodingly.

[R.G.]

I am a fan of the TQ2 series and another. I think it was the ASX series but I haven't used them since Panasonic bought the original company so I don't know if they are still stocked. Omron has a few also that can work but they are a bit more money then the Panasonics and some need alittle more current. The TQ2s are my preference. Nice size, light, a fairly standard hole pattern (so it can fit perf boards), come in many versions of voltages and coil configurations, cheap, and some of the, if not, lowest current needs.

A quick glance at the datasheets shows the TQ2 and EA2 to be same hole pattern, same voltage limits, etc. right down to the coil resistance. Digikey wants 3.50 for a TQ2 single coil latch, Mouser wants 3.23 for an EA2 single coil latch; I suspect they're NEC's and Panasonic's designs for pin-for-pin compatible. 

I prefer the dual coil latching because it has always seemed simpler to me to pulse two different places to reverse a relay instead of flipping two points two different directions. I suspect that's just me, and it's about the same, just a different approach.

I never really understood people using 9v relays in battery effects. Its fine for line powered systems but with batteries most effects will still be operational long after the minimum voltage required to operate a 9v relay has passed. Kind of wasteful. I have found that most effect circuits die before the typical 9v battery runs out of enough current to still be able to energize a relay coil at lower voltages. It does require extra parts and designing but it allows you to stretch out the life of the battery. I've been doing it for many years.

Any kind of relay at all that's energized all the time is kind of wasteful in a battery system. Relays, being electro-mechanical and not electronic, simply take too much current to be held on all the time on batteries. I agree with you - that's why I posted the single-IC latching relay drive bypass circuit at GEO (http://geofex.com/FX_images/ltchrly.gif) years ago, to make this easy.

It's funny that although miniature latching relays make this feasible now, we're seeing a relaxing of the mantra that only hard-metal true-bypass is any good, and also fewer and fewer pedal setups that actually run powered by batteries in working-musicians' setups. There's nearly always AC power available, if only because the amp needs an AC plug.

[drewl]

At work we use some Aromat 5v dc  that work fine on 9v, or even up to 12v with no problems.
I've used some in amp builds and they work great, no need to use them in pedals.....so far.

[MikeH]

Unscientific, bad engineering, dirt stupid approach.  But it'll work. 

Pretty much sums up my usual approach entirely