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|1/18/2001 3:53 AM|
||NTE-103A for Fuzz face is GOOOD!|
I can now personally reccomend this transistor, at least over the nte 158 for FF clones. I like the thing a lot but admit I only have about an hour playing with my newly changed over arbiter ckt.
The biggest diff that I noticed was a much improved frequency range. The 158's were really muddy and completely unsatisfactory in that way. The 103a's have all the treble I want without being to bright. I still have to mess around with it and check the gain of the devices I have and some other minor tweaks I wanna try but the 103's are a hit for me.
Now, Where did I put that printout of RG's fuzz face article????
|1/18/2001 5:34 AM|
AHA! So you built a NPN fuzz face! I will have to keep my eyes peeled for 103 types. My local surplus place lists the devices by their NTE number, even when the tranny is something else that crosses to the NTE #.
In other words, they are crossing backwards.
I found 2sb172s,b172, RCA2n109, and others by asking for nte102!
I don't buy the NTE germs new, they want over $2 each for them, and I have heard they are very inconsistent.
Try putting a silicon 2N3904 [or equiv] in Q1, you might find that it improves the clarity and attack without losing the cool FF feel.
|1/19/2001 12:02 PM|
Oh yeah. I had to try it.
Can you get the cross ref info for some other nte products?
like the 100, 101, 102??
See my next post though, things have gone downhill from where I last left you,
|1/19/2001 7:00 PM|
The 100 lists as PNP Ge
101, NPN Ge
The ecg cross ref program is great . I listed it over at Aron's, I don't usually duplicate, but this is good:
ECG link :
Go to 'download ECG Instant Cross version 2.2'
Takes a few minutes, then you have a built in ref file for crossing right in your computer, don't even have to go online. It is very fast to use, way faster than the NTE thing. The only disadvantage is you don't have the data sheets. If you need the data, then you can log onto the NTE site. Enter most any NTExxx # as ECGxxx, and the part will come up.
In other words, NTE numbers and ECG numbers are almost all the same.
|1/19/2001 12:12 PM|
||WHOAH!! Wait a minute!!|
Before you go out and buy a bunch of those NTE 103a's listen to this.
I was playing My FF last night and decided to swap the position of the transistors to see If that had any effect on the sound. I had not measured them for gain yet. I pulled them fromtheir sockets and swapped them around and the thing didn't work. I checked that I had put them in correctly etc and no problems so I swapped them back to were they came from and NO GO.
I could only get sound out when I played realy hard and then it would only barelt break through.
Good time to test for gain/leakage. Well, By my calculations, each piece has a leakage above 450ua and rising depending on how warm they are. I assume that when I pulled them and swapped their placement I overheated them. Oh, The leakage did rise a lot when I had them under test and touched them. That is amazing. The heat from my finger could cuse that much diff.
Tonight i get out the 3904's and a cube of ice and see where Iget from there.
Deeper and deeper I go, Firefly
|1/19/2001 11:20 PM|
||Help with leakage calculations.|
I have read and re read RG Keens article on picking transistors for fuzz faces and want to bounce this off someone to see if my math is correct or flawed.
What I want is a formula to find leakage cuurent from the voltage across the 2.4k resistor used in the fuzz face transistor checker from RG's article.
So I need a formula like:
Vl(in volts) * X = Current in microamps
RG tells us that 1 milliamp gives 2.472 volts so 1000ua(microamps) = 2.472volts
now good ranges for leakage current are listed as 0-300ua. So how to find for 100ua I set up the ratio
------ = -----
so back to the original equation I need:
volts * X = current in ua
so: .2472 * X = 100
where X = 404.53
so volts * 404.53 = current in ua
in my case leakage voltage of 1.08 volts so:
1.08 * 404.53 = 436.89ua
IS that at all right???
Thanks for following that if you made it to the bottom.
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