Convert latching signal into momentary

[trixdropd]

I have a Carl martin Octaswitcher 2 that has a 1/4" "latching switching" function assigned to the presets. My amp needs a momentary pulse so the two don't play together well. I want to make a box that lets the latching jack send a momentary pulse to the amp.
This has got to be simple right?

[armdnrdy]

You are missing a lot of information regarding what type of logic signal your amp requires.

Does it need a single pulse or a pulse of a certain duty or duration? Which logic CMOS, TTL?

Do you have a compatible controller for the amp that you can take a look at?

You're going to have to supply this info before anyone can make any suggestions.

[trixdropd]

You are missing a lot of information regarding what type of logic signal your amp requires.

Does it need a single pulse or a pulse of a certain duty or duration? Which logic CMOS, TTL?

Do you have a compatible controller for the amp that you can take a look at?

You're going to have to supply this info before anyone can make any suggestions.

I didn't take the pedal apart. I have the pinout for the connector though. There are 4 switches and 3 leds. All share a common ground, and each channel and led has a + wire. When I connect the common to one iof the channel + pins (with a paperclip) the amp switches as well as the led for said channel on the amp face.

I did a continuity on the pins on the pedal itself and it seems to be just simple momentary switches that are n.o.. I don't believe there is any logic in the pedal itself and my tests worked with no power to the pedal.

So on the latching side think of a mono guitar jack that connects tip to sleeve when activated. It's isolated by relay. On the amp side, I just need to connect the + on the 4 channels to ground for a blip via 4 channels of logic.

I hope that helps...

Here is the pinout on the amp
Pin 1 - Clean LED +ve leg
Pin 2 - OD1 LED +ve leg
Pin 3 - OD2 LED +ve leg
Pin 4 - Reverb LED +ve leg
Pin 5 - All LED ground legs and all footswitch ground lugs
Pin 6 - Clean footswitch +ve lugs
Pin 7 - OD1 footswitch +ve lugs
Pin 8 - OD2 footswitch +ve lugs
Pin 9 - Reverb footswitch +ve lugs

[trixdropd]

This can't really be that hard can it? I did some testing on the amp. It is not picky about the pulse length. If I continue to hold the (momentary) switch down the amp selects what it's supposed to once. I still want pulses though.

help?? 

[PRR]

> This can't really be that hard can it?

Yes, it is.

We have to act on either a rising *or* falling edge. This leads me to all sorts of complicated rectifiers or inverters and OR-gates. There is a better way, but not something I use daily (or even decade-ly).

It is not clear (from you, or from Martin) how much load the Octo can stand. (So a certain Mickey-Mouse logic which worked on my '67 Cougar may blow-up the Octo.)

Do you have convenient and ample power for relays?

Do you have relays in mind? How much pulse energy do they need? (Mid-size relays, 1mS pulse won't even start the clapper, 10mS may, might need 100mS to get a for-sure clack, 500mS gets into problems with possible rapid 2-clicking; and relays vary all over the place.)



There is surely a part which combines an XOR function with a power driver. However I'm not going to search for hours when '4030+'120 is 2-bucks for two outputs.

"XOR" is a (C)MOS gate chip such as:
CD4030BE
HCF4030BEY

"CD" is old classic CMOS, good to 18V.

"HCF" is a newer MOS process, good to 22V.

In either case, "B" suffix is strongly preferred.

In the ST brand, "E" suffix is DIP (big enuff to see). Other brands may use "N". You probably do not want SOIC (teeny-tiny). (If you do favor SOIC, you'll know what to do.)

"Y"? I have no idea.

4030 is a 6-pack. You only need two gates. On the other four gates, wire all inputs to ground, leave all outputs not-connected.

4k7 to logic power is pull-up.

Relay pulse width is set by R1 C1.

100K resistor is simple protection for the chip's naked input.

TIP120 is good to 60V 5 Amps (it can whack the starter-relay in your car). In this app it needs no heatsink to almost 1 Amp (signal relays use much-much less). The metal tab must not touch ground.

It is Good Practice to shunt the relay with a diode. However small relays on the beefy TIP120, I have never found this to be necessary. IMHO the relay can't slay the '120, and a diode is one more thing to fail for no reason.

"esp" is credit to Rod Elliott.

[trixdropd]

> This can't really be that hard can it?

Yes, it is.

We have to act on either a rising *or* falling edge. This leads me to all sorts of complicated rectifiers or inverters and OR-gates. There is a better way, but not something I use daily (or even decade-ly).

It is not clear (from you, or from Martin) how much load the Octo can stand. (So a certain Mickey-Mouse logic which worked on my '67 Cougar may blow-up the Octo.)

Do you have convenient and ample power for relays?

Do you have relays in mind? How much pulse energy do they need? (Mid-size relays, 1mS pulse won't even start the clapper, 10mS may, might need 100mS to get a for-sure clack, 500mS gets into problems with possible rapid 2-clicking; and relays vary all over the place.)



There is surely a part which combines an XOR function with a power driver. However I'm not going to search for hours when '4030+'120 is 2-bucks for two outputs.

"XOR" is a (C)MOS gate chip such as:
CD4030BE
HCF4030BEY

"CD" is old classic CMOS, good to 18V.

"HCF" is a newer MOS process, good to 22V.

In either case, "B" suffix is strongly preferred.

In the ST brand, "E" suffix is DIP (big enuff to see). Other brands may use "N". You probably do not want SOIC (teeny-tiny). (If you do favor SOIC, you'll know what to do.)

"Y"? I have no idea.

4030 is a 6-pack. You only need two gates. On the other four gates, wire all inputs to ground, leave all outputs not-connected.

4k7 to logic power is pull-up.

Relay pulse width is set by R1 C1.

100K resistor is simple protection for the chip's naked input.

TIP120 is good to 60V 5 Amps (it can whack the starter-relay in your car). In this app it needs no heatsink to almost 1 Amp (signal relays use much-much less). The metal tab must not touch ground.

It is Good Practice to shunt the relay with a diode. However small relays on the beefy TIP120, I have never found this to be necessary. IMHO the relay can't slay the '120, and a diode is one more thing to fail for no reason.

"esp" is credit to Rod Elliott.

Thanks for the insight. I am gonna order the parts and experiment.
I have 9vdc available. I have a couple different relays handy, latching omron g5v-2-HI-DC9V and as well as some 5 volt AL-5WN-K latching relays. Are either of those sufficient? 

As for the octaswitcher, the relays should be able to sustain an amp I'd think.

[slacker]

I don't think you can use latching relays that will defeat the point of the latching to momentary converter, one pulse will turn the relay on the next one will turn it off, so you'll just be back where you started. You need unlatching relays so they are only closed for the length of the pulse.

[PRR]

Latching relays?? WHY??

What Ian said. You HAVE latched outs on the Octo. You want PULSE. You want change-detector with dumb relays.

[trixdropd]

Paul,

My parts have arrived and I breadboarded the circuit up with an omron relay and it works perfectly as far as I can tell short of testing on the amp. Thanks a lot for your help on this.

This amp has a feature or two more that can be switched the same way, I assume I could have 4 total switches on a CD4030BE by duplicating the whole circuit shown times minus the ic?

[trixdropd]

Well This circuit is indeed the answer to the question I asked. The problem lies in the things I didn't mention, like there being multiple channels I wanna control. With a momentary switch the amp acts like an old push button radio where you push the button, and it jumps to the channel you pushed and off the previous one it was on.

Since this circuit sends a pulse on both make AND break, using it with the octaswitcher sends signals to both channels. I found the solution with this amp (Blackstar ht-100 venue) that even though the stock footswitch is all momentary, using latching functions like those from the octa switcher work perfectly as they only pulse on the make. The pulse never shutting off doesn't matter on this amp.

So the solution is 4 jacks, a DB-9 connector, an enclosure and some wires.

Thanks again for the help Paul, I learned a bit either way, so nothing is lost.