Relay switching help, please.

[markr04]

This is close enough to stompboxes I suppose... switching anyway.

I bought a relay switch circuit from www.tedweber.com (https://weberspeakerscom.secure.powweb.com/store/chansw.htm). I'm trying to make my amp's effects loop switchable with it. I've hunted down the correct jacks in the amp to do this, and I can get 6VAC off of a tube somewhere. But I'm having trouble with the switch pinout and correct power and ground placement.

Here are the components on the board:
D1: diode x007 (can't read the first bit)
BR1: bridge DB101G (datasheet: http://www.chipcatalog.com/Taiwan/DB101G.htm)
C1: 10v 1000uF cap
R1: 75ohm resistor
RLY1: DPDT (I assume) relay: TR99-6VDC-SB-CD
The pinout of the relay is the NO,C,NC, etc.



Questions:
1) Can you tell me what a bridge does? It has two ~ ~ where the 6VAC and ground should go. The other side of this is a + and -. I marked these on the photo in red. Does the 6VAC go to the ~ with the + on the other end?

2) I just now thought of this. Which is standard on amps (or a 5150 specifically): with no pedal present, is the effects loop normally active or bypassed? And that brings me to....

3) How do I wire this thing so that the effects loop opens and closes properly? I believe the direct line from the preamp to amp is bypassed when a plug is inserted in the return jack.

4) Is there a way to view the NO, C, NC that would make sense to me like the bottom of a DPDT stomp switch?

5) I can't use the tip+ring because that's controlling the channel switching, so I plan to use sleeve+ring. But Weber's site said "use ring+sleeve". Why is that?

6) there's no indication on the two SW pads. Does it matter which way I connect those?

Thanks in advance for your help. I've been working on this amp so long to rebuild it. Now it's working, but I want to get this thing done and put the whole thing back together.

[niftydog]

well, it's close enough... but a lot of these questions are easily answered using google!

So you effectively want a bypass for your effects loop. Is that it? Seems to me there's simpler ways of going about this.

1) the bridge rectifies AC. For more detail, search google. Connect the two AC wires to the terminals marked with ~. The rectified waveform comes out the other two terminals.

2&3) the effects loop on most amps is always in circuit, it just depends on whether there's anything plugged into the jacks. When there's nothing plugged in, a switch in the effects loop jacks is closed thus passing signal directly through. When a jack is inserted (in either the out or the return, depending on the amp design), that switch is opened. The effects loop must then be completed by connecting the other jack before any signal will pass through the effects to the next stage in the amplifier.

Thus, what you seek to do is to bypass this built-in switch and substitute your relay kit. Does this help?

4) C stands for "common". This is the common terminal of a switch pole. The other connections are NO (normally open) or NC (normally closed). Normally open terminals are open circuit (from the common terminal) when the relay is NOT energised... and vice versa.

5) this statement rings alarm bells. Are you saying that the same jack that has the effects loop signals also has some kind of switching arangement associated with it? In most cases the channel switching footswitch jacks are entirely seperate from the effects loop signal jacks.

The PCB says to use tip-ring. It also says not to ground either terminal. Since the sleeve is commonly connected to ground in every device on the planet, then using the sleeve is not recommended by the makers.

6) I wouldn't think so. All it says is to short them together.

[markr04]

well, it's close enough... but a lot of these questions are easily answered using google!

I googled the bridge's part number, hoping that would turn up the info I needed. All I got was the link. These are merely the remaining questions I had after searching for everything else. Thanks for answering them.

So you effectively want a bypass for your effects loop. Is that it? Seems to me there's simpler ways of going about this.

Yes. Will you clue me in on your ideas? I'm trying to avoid stringing two or three more cables out, or I'd just make a bypass box. But maybe you have something else in mind?

Thus, what you seek to do is to bypass this built-in switch and substitute your relay kit. Does this help?

Yes, that does help.

4) C stands for "common". This is the common terminal of a switch pole. The other connections are NO (normally open) or NC (normally closed). Normally open terminals are open circuit (from the common terminal) when the relay is NOT energised... and vice versa.

Okay. I get it now! I thought it was (C)losed. I see it as a DPDT stompswitch now. Thanks!

5) this statement rings alarm bells. Are you saying that the same jack that has the effects loop signals also has some kind of switching arangement associated with it? In most cases the channel switching footswitch jacks are entirely seperate from the effects loop signal jacks.

Yes, it's a stereo jack, a stereo plug, and a two-switch box. Here it is:
http://www.musiciansfriend.com/srs7/g=home/search/detail/base_pid/421393/
But there are many more than just this. Many of the Marshall, Vox, etc. switches sold on that site are the same.

The Weber site says:
"Both the tip and the ring must be isolated from ground in amps where the filament winding has a grounded centertap."

I don't know if the 5150 Combo has that characteristic or not.
But that quote suggests, to me anyway, that there are amps where this is not necessary. In the 5150 Combo, the tip+ring switches the channels and the sleeve+ring switches the reverb. I've already removed that function and made the reverb always on at the transistor switch (I jumpered it). So now I have sleeve+ring to work with.

"filament winding has a grounded centertap"... is this common? Old school?

The PCB says to use tip-ring. It also says not to ground either terminal. Since the sleeve is commonly connected to ground in every device on the planet, then using the sleeve is not recommended by the makers.

6) I wouldn't think so. All it says is to short them together.

Thanks for your reply! If you or anyone else have any other ideas, please tell me.

[markr04]

I found this info a moment ago, which was written by a Peavey designer(?) Roger Crimm. It is referring to the 5150. I read that as "grid is negative, filament is positive." Do I understand that correctly? If so, I don't have to be concerned about isolating grounds in my application and I can use the sleeve.


"When we refer to biasing an amplifier, that generally means we are setting the idle current for the power tubes. The idle current is just that. It is the current present when there is no signal passing through the tube. It is adjusted by changing the bias voltage, which is a negative voltage applied to the grid of the tube.
As this negative voltage is adjusted, the current at the filament will increase or decrease. Ohms Law states that Voltage = Current x Resistance. If voltage increases, then current must increase as well. As the bias voltage becomes more negative, the current becomes smaller, and the tube is said to be biased "colder". As the bias voltage becomes less negative, the current goes up, and the tube is said to be biased "hotter". "

[niftydog]

What I meant was google "bridge rectifier". This would have told you what their main purpose is.

The alternative idea is simply to build a bypass box that switches the effects send directly to the effect return, just as you have said. All external, simple, no mods required. There are probably a few ideas for such a beast floating around the forum.

Re; the footswitch you linked to.
ok, now I understand. That footswitch simply takes the tip (or the ring) and grounds it when the switch is activated. Note that "grounding the tip" is actually just the same as "connecting the tip to the sleeve!" This is unsuitable for your needs. You will either need to modify it so that the switch connects the tip to the ring or build a new footswitch box. I would suggest that you build one rather than effectively disabling a perfectly good footswitch as once it's modded to suit the relay project it will be useless for it's normal, intended purpose.

In the 5150 Combo, the tip+ring switches the channels and the sleeve+ring switches the reverb.

that sounds wrong to me, but I'm not an expert on 5150's! Usually, the sleeve is ground and the switching signal is present on the tip and/or the ring. Grounding the signal switches the channel/reverb. What you've said there seems to suggest that the ring is infact ground, and not the sleeve which is the common way of doing things.

Is this information in the documentation or have you worked this out by trial and error? It could be just a fluke that shorting the tip and the ring works. As I said, usually you would short the tip to the sleeve.

Even so, with the sleeve+ring to work with, I'm still pretty sure that the sleeve would be connected to ground, which again is not suitable for your needs. (Man, this project needs to be re-worked, this shorting the tip to the ring thing is totally non-standard and difficult to work with!)

I do not know anything about the filament winding questions... anyone?!?!

[niftydog]

oh, just to clarify, it says

"Both the tip and the ring must be isolated from ground in amps where the filament winding has a grounded centertap."

which is not quite the same as

"filament is positive"

[markr04]

Thanks again for the reply.

I'm lost. There are two switches on one stereo jack/plug system. It seems to me that in order for each switch to perform a different function (reverb on/off and channel switching), the sleeve would have to be used. I mean, shorting tip+ring can't control both, can it?

And thanks for clarifying the negative filament thing!

[Arne]

Hi, maby this can help.
I have a Peavey Classic 30 and a Peavey Bandit transtube and the switching on both of these amp's are sleeve to ground and tip for reverb and ring for channel.

Arne.

[Transmogrifox]

It seems pretty straightforward to me.  Let's break it down:

6 of your pads are the equivalent of a DPDT switch.  You seem to know what to do with that.

This leaves 4 pads, two are for your 6V AC filament voltage.

The other 2 are for the switch.

Starting with the filament voltage, you have an AC supply  whose positive and negative reference in the the generic case are unknown.  It may be that one is ground, or perhaps they are both offset from ground.

When you connect the switch, you simply complete the DC circuit through the relay coil and it energizes the relay.


So all you need to worry about is the equivalent of two wires coming out of SW1 and SW2 that do not contact anything else anywhere.  When you want to switch on, these two wires are connected to eachother, and nothing else.  It should be the equivalent of putting a jumper between the two pads when the switch is closed, and the equivalent of leaving them untouched when the switch is open.

So whether you use the tip, ring, sleeve, a lampshade or horse dung, just make sure the above conditions are true in the way that the remote switching wiring connects those two terminals.  If you use the sleeve, make sure the sleeve is not grounded.

[RedHouse]

It's interesting that Ted Weber is using a 28vdc relay off the 6.3vac heater supply, rectified that still would only be like 8.9, must be enough to kick it over reliably though.

markr04, didn't you get a diagram with it from Ted? I though he included a diagram with the board kit.

[Transmogrifox]

It's interesting that Ted Weber is using a 28vdc relay off the 6.3vac heater supply...

TR99-6VDC-SB-CD

It's not a 28VDC relay, it's a 6VDC relay.

Also, rectified 6.3Vrms is approximately 6.3VDC.  RMS is equivalent to integrating the absolute value of the wave form over one period assuming a periodic voltage cycle.

6.3Vrms for a sine wave actually has a peak amplitude of 8.9V.

[niftydog]

It seems to me that in order for each switch to perform a different function (reverb on/off and channel switching), the sleeve would have to be used. I mean, shorting tip+ring can't control both, can it?

yes, that's what I said. But you're getting confused between what is standard for the 5150, and how Ted Weber designed his circuit.

This project seems to simply rely on two terminals being shorted together, neither of which are ground. It's really as simple as that. The fact that Ted chose tip and ring is simply because he wishes to avoid people inadvertently connecting the circuit to ground - due to the fact that sleeve is almost always connected to ground!

Unfortunately, that design concept flys in the face of years and years of standard practice for amp designers all over the world.