#SIGNAL PATH OF A TRANSISTOR HOW TO#
#SIGNAL PATH OF A TRANSISTOR FULL#

This gift was given to me by my friend Craig

There's a really cool way to debug your circuit besides the look and guess/measure

Once you are satisfied that your components are getting power, make an Audio Probe (see below) and trace through the circuit.ДЄ technique for debugging a 9 volt stompbox circuit (Audio Probe).

If you are testing the board in the enclosure and it worked while it was out of the box, look for any place the enclosure or a pot might be touching the board or a wire and grounding out the circuit.

Twisting the board can alert you to this. Sometimes the circuit will spring to life because of a bad solder joint.

If you are desperate, you can gently! twist the board to see if you have bad solder connections.

If there are zero volts, it's possible you have a short in the circuit.

With the circuit going, measure the voltage at the battery terminal and make sure there is ~9 volts.

If your circuit uses an IC, measure the pin that gets Vcc(+) and make sure it's getting power.Triple check your resistor values throughout your circuit.Check the orientation of your electrolytic capacitors if the circuit contains them.Check the orientation of the transistor or IC, triple check to make sure that the transistor or IC has the right pins in the right places.If you're lucky, the schematic or docs will tell you a range of voltages that the transistors should be getting.

Check all transistors for reasonable voltage levels (volts not millivolts or other small value). If your circuit has transistors, measure the voltage coming from the power supply to the transistor and make sure that it is getting power.Pay careful attention to places where multiple components connect to a singe wire. Carefully trace through the schematic and follow your circuit.Connect the black lead of the voltmeter to ground of your circuit and touch the connection with the red lead of the voltmeter. Make sure that all points that are supposed to receive power really are getting power by looking at the connections and by measuring with a voltmeter.Look carefully and make sure that all points that are supposed to go to ground really do. Check all connections that go to ground or power.Keen's GEO debugging page and do what he says! :-) Check out GEO's Guitar Effect FAQ too, maybe it's a frequently asked question Here are a few suggestions for debugging your circuit. So you make your circuit and connect it up and. I have used the techniques described below to diagnose and debug many circuits. However I have built a fair number of these units.

#SIGNAL PATH OF A TRANSISTOR HOW TO#

It's become its own thing.NOTE: I am still learning how to make these circuits. Anywhere else in the chain and other pedals will muck up part of the magic.Д®DIT: Note that the newer versions of the Fatpants are only tangentially related to the original attempt to duplicate the EP preamp. if you want to sound like an EP is last in your chain, you should put an Echoplex preamp pedal LAST. That's where I was kind of going with all this. The high output impedance is, I think, part of the sound. The Madbean at least runs on higher voltage internally and has the same output impedance as the Ep-3. The Xotic really seems much less interested in copying anything about the source circuit and even has dip switches to sound like something completely different. Other pedals, like the Madbean Fatpants (one of my favorite boosts) and the Xotic EP Booster (one of many peoples' favorite boosts) mostly duplicate the frequency response - some treble cut, moderately high output impedance, some lows trimmed, and a boost in the mids. I'm tempted to say it could only happen if the preamp pedal had an effects loop you could plug your delay into. I'm not convinced you can duplicate this with just the preamp. The interesting thing that happens in the EP-3, though, and this is something that the clinch unit sought to duplicate (beyond some other tone shaping generalities) is that when the echo is mixed back in with the dry signal, it's possible to get some weird tonal things (this is probably the source of what clinch refers to as the unit's 'non linear phase response').

The signal is split to the output, and then everything else in there, all those bipolar junction transistors etc, deals with the echo path.

#SIGNAL PATH OF A TRANSISTOR FULL#

The full preamp including everything that deals with the echo may be more complicated than a lot of the pedalizations, but the dry path is actually. It did use a mix of FETs and bipolar junction transistors (schematic here if anyone's interested: ). But the EP-3 is the one everyone's concerned with. Some of these are worth knowing about because they can affect where you want it in the chain.ДЇirst, the earliest units had tubes, and recreating that sound in a solid state device IS best done with FETs. There are some aspects of the echoplex preamp that are echoed in all the pedalizations.

Signal path of a transistor