Texas cattledrive from weber

[jamie cowan]

does anyone know the names of the pins on this germanium? Looks like I only need three







This is my first build besides several Tilman jfet preamps

Thanks !!

[justin.ray]

Is there a code printed on the transistor?

[jamie cowan]

v on top
tt313a 8403 on side

[jamie cowan]

Originally Posted by jamie cowan

v on top
tt313a 8403 on side

maybe it is 1t313a 8403

[justin.ray]

hmm... I couldn't find a data sheet, but I think that the 1t3113a designation is correct. I think you'll have to get out the multimeter. Here's some instructions: http://www.allaboutcircuits.com/vol_3/chpt_4/3.html

Just keep in mind that your Ge transistor is a PNP transistor. That fourth lead is strange, it might be a ground for the body? really strange...

If the article is a bit much, let me know and I'll try to post a simplified version this evening.

[jamie cowan]

Originally Posted by justin.ray

hmm... I couldn't find a data sheet, but I think that the 1t3113a designation is correct. I think you'll have to get out the multimeter. Here's some instructions: http://www.allaboutcircuits.com/vol_3/chpt_4/3.html

Just keep in mind that your Ge transistor is a PNP transistor. That fourth lead is strange, it might be a ground for the body? really strange...

If the article is a bit much, let me know and I'll try to post a simplified version this evening.

Thank you so much!
You are right about strange it is Russian.. the forth one goes to the case Idon't know what to do with that?

the others are K B and E

with the case pin on the right K is on b is top K is middle and E is bottom..

[justin.ray]

If the fourth one goes to the casing, its almost surely a ground connection. It's probably there to protect the transistor, but I would ignore it if it's not easy to connect to ground. If it's on the casing, I can't imagine what else it would be.

Did you find a data sheet for it? I ask because K is for kollektor (Russian). They made a lot of crappy electronics before/during the cold war that made really poor radios but ended up being pretty rad for dirt boxes. The only problem is that they tend to be pretty inconsistent, you would do well to follow Weber's advice and adjust R3 to 'get the best overdrive tone.' If the manufacturing process of the transistors was better/more consistent, you wouldn't have to worry so much about this, but I'd recommend a trimpot in the R3 spot, since they're only 60 cents. Unless you're going to breadboard the circuit first, then I'd just swap resistors in R3 until you found the flavor you like.

[jamie cowan]

Thanks Justin!!
The folks at Weber are going to send me spec sheet on it..
one question The schem says r3 is from 150k to 470k... If I plug in a trim pot what one should I use? Will I hurt anything if I am lower than 150k. ok so two questions whoops
Thanks again!
Jamie

[justin.ray]

I'd recommend a 500k trimpot, so you can get the full range of adjustment. As far as going below the 150k recommendation, I don't think that you can damage the transistor by reducing this value. You can get semi-fixed trimpot or put a trimpot in series with a 150k resistor if your worried about it.

http://www.electronics-tutorials.ws/...ier/amp_4.html

Part of the way a transistor works is like a diode, it only lets current through when the polarity (i.e. positive or negative) of the signal is correct and the voltage is high enough. So if you just apply the AC signal without a DC bias, you would, at best, only get half of the AC waveform, because the midpoint of the AC signal is 0V and half of the waveform is the wrong polarity. So, in order to get the other half, you use a DC signal to make the midpoint of the AC signal high enough for the side of the waveform that is being left off to be above the cut off voltage of the 'body diode'. The second diagram on the link above is an okay picture of what I'm talking about.

Using a trimpot for R3 would be a great way to understand how biasing works, which is a pretty handy thing to know when it comes to dirt boxes.