New KF-50 Done tonight...this ones mine!!!

[Roe]

any good DPDT switching kits?

[Structo]

Yes what is the status of the switch kits Dana?

Is it possible to use these on a ODS type amp for switching the PAB, OD, Mid boost, etc?

A solid state switch sounds much more reliable-durable than relays.
Also probably less likely to induce hum into the signal path.

[marcoloco961]

I was curious, this is an interesting thread and a couple of cool little SS chips to help mix the new with the old. I am wanting to add a switch to my amp to toggle between 1.5k and 5.6k on the power tube grid resistors. I was thinking I could switch in a couple of 2 k resistors in parallel with the 5.6k's to accomplish this and this switching set-up seem to fit the bill for the silent switching and FS capabilities.

I noticed that early in the year the kits were soon to be available. Then it seems the thread kind of just ended quietly. Are the kits available? I don't see them listed on Dana's site. If they are being made available, who has them? Thanks.

[M Fowler]

I finshed my K60 a long time ago and never received any response for my email request for fast/gradual foot switch.

[UR12]

I finshed my K60 a long time ago and never received any response for my email request for fast/gradual foot switch.

I usually only use these in my own builds. I have some switches available but I haven't had time to get these on the website. I have no instructions written up but can provide you with a schematic. Maybe when I get time I can write some up and add them to my webpage if there is any interest. PM me here if your interested. I need to know the application and if you have a source for 5v ac or not. If you don't have an unused 5 volt winding you will have to add a small transformer that I can provide.

These are only SPDT at this time. I have some DPDT boards designed for a customer but they are not available at this time

[marcoloco961]

I grabbed a few of the chips from mouser and have been fiddling with them. Just bench testing circuits right now to get an understanding of exactly how they work, but they seem to open up an unlimited realm of "quiet" and "multi" switching options. Like I said, I wasn't really looking for a fast/gradual switch, I was going more for a switch to toggle resistance values on grid resistors, but I think these chips and switch set-up should work for many different applications. Originally I had intended on using a faceplate mounted switch, but after seeing this thread, I thought a footswitch option for switching would be very handy.

I have got the basic operation of the opto and inverter chips figured and the required resistances needed to get them to do what I want them to do. Just need to do a working test on an amp to complete tests. I plan on giving it a try when I get the "bench" amp assembled.

The kit version would eliminate alot of fiddling, as they are already assembled and bench tested, that's why I was wondering why we haven't heard anymore on these cool little babies.

My wife says I have enough cool toys already, but I think there is room for just a few more........

[Structo]

Do these chips switch instantly like a relay does or is there a delay?

What level of voltage or current can they safely switch in comparison to relay contacts?

Edit:
OK I looked them up at Mouser.

Part # PS7141-2A-A

Looks like 400v 150ma load limit.

Am I reading the specs right for the turn on time? >10 ms?

[UR12]

Do these chips switch instantly like a relay does or is there a delay?

What level of voltage or current can they safely switch in comparison to relay contacts?

Edit:
OK I looked them up at Mouser.

Part # PS7141-2A-A

Looks like 400v 150ma load limit.

Am I reading the specs right for the turn on time? >10 ms?

\

That looks right for the voltge and current ratings turn on time is .35ms and turnoff time is .o6ms

[Structo]

In researching the data a bit more, it doesn't seem that the SSR is the way to go to switch AC signal voltages.
Because of the internal resistance of the MOSFET it would degrade the signal.

These are what I came up with for disadvantages for SS relays.

-Fail short more easily than electro-mechanical relays

-Increased electrical noise when conducting

-Higher impedance when closed (-> heat production)

-Lower impedance when open

-Reverse leakage current when open (µA range)

-Possibility of false switching due to voltage transients

-Isolated bias supply required for gate charge circuit

-Higher Transient Reverse Recovery time (Trr) due to the presence of Body diode

For instance in the Dumble amps, we use relays to switch the overdrive channel on and off, and another one for the PAB or boost circuit.

On the OD channel we use a DPDT relay that switches several things in order for the overdrive to come on.


Maybe I'm wrong but it seems that switching small ac voltages is not something these would do well, no?

[soma_hero]

I used SSR switching on my Trex, and it sounds great. Everything sounds as it should.

That switching scheme uses the normal 6.3V heater, rectified to provide filtered DC, the exact voltage doesn't really matter as long as it's between max and min requirements.

Switching is between the grids and ground of two stages and disconnecting negative feedback loop. Handles all of it fine...

[UR12]

No signal degradation (From the data sheet) They are suitable for analog signal control because of their low offset and high linearity.

No Heat (We aren't talking about switching B+ to preamp tubes or anythig like that) They are only good for about 300 mw

As far as low impedance i don't see a lot of difference between the off state at >100 meg ohms and a open contact on a relay. Especially if you have to add a 2-5 meg resistor across the points of the relay to keep them from popping.

No switching noise to speak of unlike a contact bounce on a relay and they draw less power than a relay

I have no idea what bias supply you are talking about,

There has been absolutly no false switching because of voltage transients. These are controlled with TTL logic circuits and run off it's own seperate power supply that is regulated and filltered. Pull up resistor are incorporated in my circuit so there is always a hi or low level present on the input to the control circuitry no matter what else is going on in the amp. In addition to that the control circuitry is opto isolated from the circuit being controled. Unlike a mechanical relay they sould never wear out.

I am using one of my boards to control front panel LEDs and two other switch boards in one of my amp designs. It switches channels, it switches a presence pot and high cut control in and out and switches in a couple of resistors . All of that from a single footswitch. This requires 3 chips instead of one relay but has worked flawlessly for about 2 years now in an amp that is gigged with every weekend.

If solid state devices worries you that much then just stick with your relays. If it works don't fix it.

[marcoloco961]

From what I have found experimenting with the chips is that the inverter chip needs a steady 5VDC feed on pin 14 and ground to pin 7. You also need to connect each unused input to the ground rail or the 5VDC power rail for the chip to work properly.

1A= input 1Y = output. any voltage less than .7 VDC is considered low state and the correlating output will be at approx. 4VDC. At .7VDC the voltage on the output leg will begin to fall gradually until you reach 2VDC. At 2VDC the output leg has approx.08VDC and has been esentually turned off. Now if you jumper the out put to the next input on the inverter you can achieve a switching between two seperate states. Pin 1A goes high, it's output and the next input go low, meaning the 2nd ouput is 4VDC. Shunt pin 1A to ground, it goes low, it's output goes high along with the input of inverter 2. Inverter 2's output then shuts off.

Cool thing is you can use 1 - 2VDC control leg to switch several inverters between 4VDC or 0VDC all at once. As someone mentioned eariler, acheiving several different functions with one switch.... I.E. Switching grid resistance, cutting or boosting gain and adding a conjunctive filter loop all at the same time. Cool little chips, IMHO.

Yet no one will say, are there any kits for sale or available?? Is it all being handled through PM's?

[UR12]

Yet no one will say, are there any kits for sale or available?? Is it all being handled through PM's?

I have some available but I need info about your application before I can give you a price. I don't want it to appear I am spaming and trying to hock my wares on the forum so I would prefer a PM so we can talk about your options.

I just sent one to Rawnster and he installed it in an amp to switch a tone stack lift in and out. Maybe he can chime in and give you a review of how he set his up.

[marcoloco961]

Cool, thanks for the info Dana. I am building a bench model wreck, so I can fart around with some of the different options available. When I have tried a few different things and have made up my mind on a final option, I will send you a PM. I can see how this idea has went from one switch to a ton of different options available. The biggest problem will probably be making up my mind on a (final) decision of what I want..LOL.

[mclmk8d]

Allyn,
Not only does that look peachy keen (when's the last time you heard THAT???), but I also really like the adjustable stand that you put the chassis on during build. Do you have plans for that to share?
Serge