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Topic:
Changing continuous 12V trigger to pulsed on/off trigger for Proceed Amp 2, 3
This thread has 39 replies. Displaying posts 1 through 15.
Post 1 made on Thursday May 28, 2009 at 10:38
zzzzdoc
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Ran into this issue and designed a box to convert the 12V continuous trigger signal from an Anthem D2 to a pulsed on-off signal that the Proceed Amp 2 and Amp 3 require to turn on off.

I've never run into a device that needed pulsed signals (3-18 V for at least 100ms) to turn on and off. It's such an odd way of doing things.

Anyone else run into this and have a different solution to the problem?
Post 2 made on Thursday May 28, 2009 at 11:02
1911Guy
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I have used this part to solve the same problem with a Mark Levinson amp. Same company as Proceed

[Link: xantech.com]
"...and that's the way it is" Larry Potterfield
Post 3 made on Thursday May 28, 2009 at 12:24
Ernie Bornn-Gilman
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Do you mean the constant on is converted to a single pulse, or to a pulsed signal with repeating pulses? Just curious.

What did your box do? I can't tell you if I have a different solution without knowing yours. I'd probably use a transistor, some resistors, and some capacitors, if it's to come out as a single pulse. If a repeated pulse, a triggered oscillator. That's a few more parts, but not too many more.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
OP | Post 4 made on Thursday May 28, 2009 at 13:24
zzzzdoc
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Actually, you need to pulse to turn the amps on, and a separate pulse to turn them off.

Odd protocol, to say the least.

I was able to do it with an electrolytic capacitor, a couple of relays, and a power supply, but it was kind of ridiculous that I had to go through the effort.

Not sure how you got that Xantech module to work, as it would only supply the on pulse, not the off pulse. How did you handle that?
Post 5 made on Thursday May 28, 2009 at 21:13
Ernie Bornn-Gilman
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You say the Anthem has a pulsed on-off signal. You say "a," so it's one signal. You say on-off, so it's a toggle. One pulse to turn on, same pulse over same wire to turn off.

And yes, the Xantech would have to receive 12 volts as a turn-on signal, then have no voltage, then twelve volts as a turn-off signal, perhaps running the signal throught a CC12 relay.

Come to think of it, 12 volts on could be a nice pulse if you put 50k across the 12 volts, run it through a 100 mfd capacitor, then put 1k from capacitor to ground. The pulse is formed across the 1k resistor. It would take a bit of time before another pulse could be sent, the time it takes for the cap to discharge through the 50k resistor.

It's ridiculous that you had to go through the effort. It's even more ridiculous that a modern device uses pulses to control toggled power. The Anthem is the source of ridiculousness here.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
OP | Post 6 made on Thursday May 28, 2009 at 22:32
zzzzdoc
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I should clarify. The Anthem continuously produces a 12V trigger signal when on, and it turns off when the Pre-Pro turns off. The Anthem isn't the issue, it's the Proceed amps. They are the ones that require the odd protocol for turning on and off. As far as I know, all modern gear just sends out 12V over it's trigger outputs when on. The Anthem is even versatile enough to include 3 trigger outputs, with 2 different current draws.

I thought about an RC circuit like you suggested, but instead just ran the capacitor to ground and it flips the relay again when it is sufficiently discharged. Same idea as you are suggesting, just simpler for this application.  Separate on/off RC circuits each with a relay one attached to the NO and one the the NC would do the same thing, just would take a few more parts. 1000ufd decays in a little less than 1 second, so the pulse is of sufficient length for the Proceeds circuitry.

I'm just amazed that I had to go through the effort for the Proceeds.  What was Levinson thinking?

BTW, I may have screwed up the below schematic. I suck at drawing them, but the circuit works, which is all that really matters.

Continuous to pulse on/off trigger converter circuit
Post 7 made on Thursday May 28, 2009 at 22:52
Ernie Bornn-Gilman
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That circuit definitely changes constant 12 volts into a pulse, but I'm missing a couple of things.

First, if you had bypassed the first relay and just put 12 volts from the Anthem into the capacitor, then taken the - side of the capacitor and run it to the Proceed, you'd have a pulse. In that case the second relay would only be there to bleed the cap, and in my case I put a resistor from + of the cap to ground to discharge it.

But if I understand correctly, you need one pulse to turn on the Proceed and another identical pulse to turn it off. I don't see how this does that.

I like the capacitor charge idea, though -- I used to have one of those 70 horsepower Austin Powers Anglias (1970) and I put a BEEEG horn on it, run through a circuit similar to this. Hit the horn once, and you got the anemic Anglia horn while charging a capacitor. Hit the horn again within three seconds, you got an air horn!
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
OP | Post 8 made on Friday May 29, 2009 at 05:40
zzzzdoc
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In the first relay position is in its native (NC) position, the electrolytic capacitor is discharged. The relay is not active.

When the 1st relay is flipped to the +12V position by the Anthem, the electrolytic capacitor is charged to +12V via the relay winding resistance. The pulse charge current through the capacitor and the relay will close the relay switch momentarily. When the relay is flipped back to ground (the Anthem turns off), the capacitor will discharge, again activating the 2nd relay momentarily. Thus the Anthem trigger can be transferred to the Proceed as if a key was pressed momentarily. A 330uF (micro-Farad) capacitor and 12V relay (260 Ohm resistance) will give about 0.2 seconds ON-time. In my case, a 1000uF capacitor provides about 3 times that time. The time is not really critical for the Proceed so long as it is greater than 100ms. I just wanted it to be long enough so I could see it on my digital multimeter to test it.

Anyway, that's the best explanation I can come up with. I originally thought that your approach was necessary, but an extensive web search suggested this, which does work. I was skeptical too until I built and tested it. Also also thought a resistor to bleed off the capacitor was necessary, but this kills too birds (triggers) with one stone.


If you want to try testing it, just build this:

Switch instead of relay to trigger momentary relay through capacitor

I know that looks stupid simple, but it does work. Anyway, I'm not an EE so this is hurting my brain.
Post 9 made on Friday May 29, 2009 at 22:52
Gizmologist09
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The best bet would be a small 555 timer circuit called a power-up one shot. This circuit can be found all over the web and gives a clean short duration output pulse when continuous power is applied to the 555 circuit. 555s can operate between 5-15 vdc and source or sink the output to trigger a small relay or transistor- based relay trigger.

The amp you are using evidently utilizes a flip-flop circuit internally to control its power supply so sustained current from an external source is not necessary.

This type of flip flop is extremely common.

Google 555 timer circuits and you will find hundreds of very simple apps.

I would hesitate to rely on the cap/relay circuit for long. The current draw on the cap by the current inrush of the relay will break down the cap and as the cap degrades, the current / voltage supplied to the coil will eventually cause the relay to chatter as the supply voltage decays. Depending on the input pulse time required by the amp, the chattering may actually toggle the amp on and off rapidly.
Post 10 made on Saturday May 30, 2009 at 00:11
Ernie Bornn-Gilman
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On May 29, 2009 at 22:52, Gizmologist09 said...
I would hesitate to rely on the cap/relay circuit for long.

I built a similar circuit in the early seventies with capacitors about the same quality as in the illustration. That circuit took a pulse and divided by two. It worked twenty years later when I last saw it.

The current draw on the cap by the current inrush of the relay

Do some math. It's twelve volts and 260 ohms. That means the "inrush" will be a giant 46 mA. Capacitors can easily see that much ripple current 120 times a second when filtering an amp of rectified AC current.
will break down the cap and as the cap degrades, the current / voltage supplied to the coil will eventually cause the relay to chatter as the supply voltage decays.

I don't think so.

Depending on the input pulse time required by the amp, the chattering may actually toggle the amp on and off rapidly.

He said it needs more than 100 msec, so it won't flutter.

On May 29, 2009 at 05:40, zzzzdoc said...
In the first relay position is in its native (NC) position, the electrolytic capacitor is discharged...

No need to quote the whole thing. The circuit is a bit of genius. And when it comes to constructing something like this, it's easier than a 555 timer and can be done much more rapidly...which for us means less expensively.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 11 made on Saturday May 30, 2009 at 00:22
Gizmologist09
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Different experiences and preferences for different folks.

Manufacturers of capacitors have decried this use for years.

If the relay concept was as reliable as a solid state circuit which delivers a stable time constant and bounce-free response, why have manufacturers superceded the use of relays with monolithic circuitry in even the simplest devices?

Not to mention the fact the the 555 version would be about 1/10 the size of the relay concept shown with a cost parity using Rad Shack parts.
Post 12 made on Saturday May 30, 2009 at 07:34
John Pechulis
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On May 28, 2009 at 10:38, zzzzdoc said...
Ran into this issue and designed a box to convert the 12V continuous trigger signal from an Anthem D2 to a pulsed on-off signal that the Proceed Amp 2 and Amp 3 require to turn on off.

I've never run into a device that needed pulsed signals (3-18 V for at least 100ms) to turn on and off. It's such an odd way of doing things.

This is a fine example of taking a simple concept and overly complicating it. Why is it engineers feel they need to improve upon an idea by designing a complicated version of a simple concept?

If the amp turns on and off with the same momentarily high signal, I could see how this could potentially become an issue. Should a signal be missed, it could cause the amps get out of sync with the preamp, unless there is some sort of feedback. A feedback loop would certainly resolve any potential issues, but then the circuit ends up being more complex, can be more prone to failure and becomes more costly to implement.

Didn't these guys ever hear of K.I.S.S.? (and no, not the band)

JP
Post 13 made on Saturday May 30, 2009 at 12:07
Gizmologist09
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Guys the whole concept of remote controls is based on pulsed data streams and alternate action switching. Cell phones turn on/off with alternate action switching using the same button, power switches on all remotes deliver a short pulse duration to the flip/flop in the microprocessor to activate triac or transistor switching.

The professional AV presentation industry has thousands of devices that use flip/flop circuitry for power up/down sequencing. This is not a new or unique concept.
Post 14 made on Sunday May 31, 2009 at 20:44
Ernie Bornn-Gilman
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On May 30, 2009 at 12:07, Gizmologist09 said...
The professional AV presentation industry has thousands of devices that use flip/flop circuitry for power up/down sequencing. This is not a new or unique concept.

No, it's not, but in professional custom installation remote programming, the first thing we look for is ZERO TOGGLES, instead relying on discrete codes for control. Toggles give us action, discretes give us control.


I totally forgot an important detail last time I wrote: If you charge up that capacitor, then leave the system on for, say, two days, it's very likely that the capacitor won't have enough charge to bounce the relay once and turn off the amp.

It's not a big deal to engineer something so that a variation in capacitor value of as much as 50% doesn't materially affect how something works when you're supplying electrons on a regular basis and depending on its time constant, but it's a bad idea to depend, really depend, on a disconnected electrolytic to maintain a charge for more than about five minutes. If it works all the time, you're lucky, and I'd expect it not to work for too many years. If you really want to make a circuit like that and have it work perfectly, use 600 volt oil-filled caps (2 mfd is about the size of a pack of smokes) and enclose them in a low humidity encasement. I am now not in favor of that circuit due to self-discharge of the electrolytic.

On May 30, 2009 at 00:22, Gizmologist09 said...
If the relay concept was as reliable as a solid state circuit which delivers a stable time constant and bounce-free response, why have manufacturers superceded the use of relays with monolithic circuitry in even the simplest devices?

The debouncing part of this is supplied by the switched unit, that requires, what was it, 130 msec to respond, so no, it's not inherently bounce-free.

Manufacturers can do this function IN QUANTITY at much lower costs than we can, using a 555 or whatever. Those cost less than the relays, are smaller, but require a PC board, assembly, and power that it would cost us more to implement if doing one or two.
Not to mention the fact the the 555 version would be about 1/10 the size of the relay concept shown with a cost parity using Rad Shack parts.

Maybe 1/10 in volume, but a 555 on a PC board has a footprint as large as that relay.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 15 made on Sunday May 31, 2009 at 21:08
Gizmologist09
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Question for you: why do you suppose the manufacturers use pulsed triggers?
Could it have something to do with design efficiency?

Second, every RF and wireless remote use a pulse trigger from the microprocessor to cause a flip flip to change from one state to the other. You can use an SCR to latch on for a DC load but all it takes is a pulse to gate the SCR on, but you must then break the DC supply to stop conduction.

Using a flip flop is faster, cleaner, and allows use of wireless remotes. There is no sustained closure with a remote unless it is a old style, discrete component, hardwired pickle switch.
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