Phrazemaster

Relay Flip Flop for HPF and Phase
« on: November 29, 2010, 12:07:13 AM »
Hiya gang,

I'm building a green pre and I thought it'd be nice to have illuminated push buttons for phantom, hpf and phase. I worked out a dpdt for the phantom and led, but for the other 2 it seems like a relay would be the way to go. So I found this circuit, which seems promising, but being pretty green with electronics, I don't fully understand it. Can anyone shed a little light on it (see link below). In the upper left of the image there is a 3v power supply, but I don't see how it even ties into the circuit at all...

And what do you think of using this to drive the hpf and phase with a dpdt, and 3formC relays...am I just making this way too hard? Maybe someone has already made a board to do this; I've spent a lot of time looking and have had some near-hits but not quite.

http://discovercircuits.com/DJ-Circuits/OnOffLatchingRelayDriver1.pdf

PS I do have some small 4pdt illuminated switches, but I thought it would be nice to use some larger "beefier" looking switches with relays instead.
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Phrazemaster

Re: Relay Flip Flop for HPF and Phase
« Reply #1 on: November 29, 2010, 12:18:12 AM »
Another possibility is this one:

http://www.fredric.co.uk/

It looks pretty good, and also looks like it has an LED built in (D3 in the circuit diagram).

Would this maybe be better?

Thanks!
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Rochey

Re: Relay Flip Flop for HPF and Phase
« Reply #2 on: November 29, 2010, 12:33:45 AM »

Please forgive the blatant promotion.

Expat audio has this solution ready to roll.

/R
Expat Audio Home: http://www.expataudio.com

PRR

Re: Relay Flip Flop for HPF and Phase
« Reply #3 on: November 29, 2010, 12:37:59 AM »
> 3v power supply, but I don't see how it even ties into the circuit at all...

Nine points marked "3V" tie together.

That's WAY more than you need. SPST feeds power to LED+resistor AND to a standard (not latching) relay with the contacts you need.


Phrazemaster

Re: Relay Flip Flop for HPF and Phase
« Reply #4 on: November 29, 2010, 01:11:36 AM »
Hi PRR, thanks...I was under the impression it's a bad idea to have the relay coils have constant power, hence the move to latching relays...then the mess of having to have an ic control the current reversal, etc...am I wrong?
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Phrazemaster

Re: Relay Flip Flop for HPF and Phase
« Reply #5 on: November 29, 2010, 01:30:56 AM »

Please forgive the blatant promotion.

Expat audio has this solution ready to roll.

/R

I appreciate it expat, I'll check it out as well. I spent so many dang hours at this, on and off for a few weeks...I think I'm finally getting a handle on it to some degree. Any special promos for this forum? If I go your route, I'm going to need to control 8 switches (4 mic pres x hpf/phase)...not so sure this will work. I already have the phantom covered because I wanted a hard-wired switch that I knew would handle the 48vdc; had a lot of trouble finding a relay that seemed able to handle it, let alone a switch which I finally found that I liked. I need just hpf and phase. Phase is already a dpdt affair, plus I need to add the LED and I want to use a momentary switch with dual coil latching relays...not sure your beautiful looking product will work with this...I'm really liking the adaptation of the rg keane circuit I posted above...
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shabtek

Re: Relay Flip Flop for HPF and Phase
« Reply #6 on: November 29, 2010, 07:12:53 AM »
can be done with fewer parts/easier; think I posted similar question a few months ago.
4013 dual flip-flop is what I am using (with driver chip following to drive heavier loads) on strip board to switch lamp and relay.
"really fine players do not use stomp boxes or master volume, they match the amp to the room and turn it up to 11.  Stevie Ray, BB King, Albert King, Duane Allman, Dicky Betts, Louis Armstrong"
   -CJ

Phrazemaster

Re: Relay Flip Flop for HPF and Phase
« Reply #7 on: November 29, 2010, 12:26:39 PM »
Hi shabtek, I'll do a search for your posts on this...honestly been searching here and other forums for weeks now on this, sometimes very frustrating to try to get info/understand...amazing such a simple "seeming" request can be so tricky...at least at first.

I will post back here later with what I find for those interested, and thank-you!
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abbey road d enfer

Re: Relay Flip Flop for HPF and Phase
« Reply #8 on: November 29, 2010, 03:19:38 PM »
What I don't like about this circuit is the use of latching relays. They are more expensive and the choice is not as large as standard relays. You can get a good DPDT relay for about $2 from a avst array of vendors. The same DPDT with latching operation will cost at least twice and the list of vendors shrinks tremendously.
A very reliable flip-flop circuit is the one used in Boss gtr effects. It drives FET's as switching elements, but you could just use the flip-flop's output (collector of Q1 or Q2) to drive the base of a transistor that would in turn drive a relay. The transistors there are not critical; almost any NPN low-power transistor will do.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Phrazemaster

Re: Relay Flip Flop for HPF and Phase
« Reply #9 on: November 29, 2010, 03:33:24 PM »
Thank-you abbey road.

I must be totally missing the point ???. I thought it wasn't a good idea to use standard relays because they have to be energized the whole time the relay is picked. Putting a long-term strain on the relay and causing sooner breakdown, plus drawing constant current.

I thought the advantage of the latching relays is they only draw current momentarily, and they last a whole lot longer because they are not constantly engaged. I have even seen warnings in the relay datasheets that they will not last as long if constantly engaged.

So is this just an unwarranted concern? I'm really a total newbie but I've logged many many hours over many months reading/soaking up what I can. I appreciate your perspective and wisdom.

Thanks,

Mike
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AMZ-FX

Re: Relay Flip Flop for HPF and Phase
« Reply #10 on: November 29, 2010, 03:44:32 PM »
I thought the advantage of the latching relays is they only draw current momentarily,

That's the main advantage. Don't know about the longevity aspect...

regards, Jack
Free Schematics and Projects - http://www.muzique.com/
My Guitar Effects Blog - http://www.muzique.com/news/
Follow me on Twitter - http://twitter.com/#!/AmzFx

abbey road d enfer

Re: Relay Flip Flop for HPF and Phase
« Reply #11 on: November 29, 2010, 04:00:41 PM »
Yes, that's really the only advantage, if power consumption is an issue (200mW per relay!)
In terms of reliability, the elements that govern the MTBF of relays are the contacts, not the coils.
I would add that theoretically, the increased complexity makes them less reliable.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

PRR

Re: Relay Flip Flop for HPF and Phase
« Reply #12 on: November 29, 2010, 06:48:03 PM »
> I thought it wasn't a good idea to use standard relays because they have to be energized the whole time

Many-many-MANY relays are "mostly ON".

With few exceptions, relays are designed to be energized "forever".

This IS a power-drain. Matters for battery power, which may be why pedal-builders are trying alternatives. Really should not matter in a studio rig.

> I have even seen warnings in the relay datasheets that they will not last as long if constantly engaged.

The LATCHING relays are not rated for constant energization. Why should they be? The whole point is a few milliSecond blip and then zero power consumption.

KISS. Wire it like a home furnace. A thermo-switch feeds a relay which feeds the blower motor. A finger-switch holds a relay which switches Phantom or phase.

Phrazemaster

Re: Relay Flip Flop for HPF and Phase
« Reply #13 on: November 29, 2010, 07:05:08 PM »
Thank-you PRR...this is exactly the perspective I needed...I really appreciate it.

So then I should use a DPDT switch, one pole for an LED for the switch, and another pole to activate the DPDT standard relay...does that sound right? Sounds a heckuva lot simpler to me...

While you're at it, any recommendations on signal level relays?

thank-you again

mike
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