More noob questions

[jfrey]

All I have found says to knock out the pin with a punch, but I tried that and the thing didn't budge.

[eatyourguitar]

Do it again

[jfrey]

Do it again

Ok. I'll try it again tonight after work.

[jfrey]

That worked by the way. Had to hit it from the other side.

Can anyone explain how gating works?

[McSpunckle]

It's done a couple of ways.

Transistor boosters are biased so that they're always on, so no matter the signal, it'll get boosted. If the bias voltage is low enough, the transistor will only be on when the voltage from the input is high enough-- thus, gating off the signal. That's what happens in a lot of fuzz pedals.

The Blue Box has diodes in series with the signal path, so basically only signals greater than .6(ish) volts get through. There was some Peavey amp that used this method too, as a noise gate.

Then there's the more complex pedals that I think use envelopes... but I've never looked at the schematics.

[jfrey]

Something like this?

gating.JPG (7.81 KiB) Viewed 1821 times

[McSpunckle]

I was actually wrong about the blue box. I went and checked the schem, and those diodes rectify the input signal, and use it to power the the output transistors-- so they're not powered if you're not playing.

You'd use two, back to back-- like clipping diodes in series with the circuit. And the diodes will need to be after a booster, since your guitar isn't going to have enough power on its own.

[jfrey]

So if the diodes are powering the output transistors, does that mean they would be going to its collector?

And, when you say after a booster, do you mean after an amplifying transistor, or after a booster circuit?

I'm confused now and I'm not sure if what I asked makes sense.

[eatyourguitar]

if you starve the collector of Q1 on a pnp fuzz face, you will get it gated. I am just looking at the fuzz factory schematic where it has a gate pot. on the fuzz factory it starves the coll of q2. same should apply to the pnp fuzz face on Q1.

[jfrey]

Anyone know any good KP mods?

[bubstance]

.

[McSpunckle]

So if the diodes are powering the output transistors, does that mean they would be going to its collector?

And, when you say after a booster, do you mean after an amplifying transistor, or after a booster circuit?

I'm confused now and I'm not sure if what I asked makes sense.

The two paragraphs of my post were about different methods. In the Blue Box, the signal goes from an amplifier stage (OP amp booster), into a diode that rectifies it (cuts off the negative side, and leaves the positive), and that's used to power the transistors on the output.

Check out the schematic here: http://www.tonepad.com/getFileInfo.asp?id=73

D2 and D3 rectify the signal (I don't really think D3 is necessary), so that only positive signal gets to the collectors of Q2 and Q3. C8 filters it, because otherwise the transistors would be off half the time you were playing. I

It's a bit confusing... don't think about it too much if you don't get it. It's only done in the Blue Box. I just thought it was a neat way of gating.

The other way, as I said was used in some Peavey amp, you just put two diodes, facing in opposite directions (like clipping diodes) in series with the signal, so that signal below .6(ish) volts (if you use silicon diodes) will get gated off. So, just like what you posted, but with another diode, facing the other way.

Here's a post on a different forum about it: http://music-electronics-forum.com/t12888/#post102916

Starving the circuit tends to gate it. Or just starving on stage (like increasing a collector resistor).

Anyone know any good KP mods?

It's a pretty simple circuit, IIRC. You could get more distortion by adding clipping diodes at the end. I think putting a low gain PNP transistor next to the transistor makes it a 33...but I might be wrong.

[hbombgraphics]

Mosfet Boost:
Mod kits DIY
Followed the instructions, at least I think I did
No sound when engaged bypass works fine.

It is on terminal strip, what should I check first?

I have a multimeter can I take readings?
Need pictures?

[eatyourguitar]

yeah, check the voltages on each pin of the mosfet reference to ground. so the black lead goes to the negative of the battery or power supply. the other probe is how you check voltages. put the meter on DC volts. picture will tell us if you wired the switch or jacks wrong. voltages will tell exactly whats not connected or bad.

[hbombgraphics]

viewtopic.php?f=149&t=21863&start=30

need help with a thingamagoop 2
Can I check the solder joints without removing the ICs?