What is the Ge temp stabilizer diode mod?

[MartyMart]

Great lookin strat
Very nice work !!

Marty.

[formerMember1]

yeah that strat is really nice!!  The marykay is great too!!  Really top quality work. 
.....
again, that is a really great pair of strats. 

[puretube]

http://www.diystompboxes.com/smfforum/index.php?topic=38046.0
http://www.diystompboxes.com/smfforum/index.php?topic=37570.0

[10acErnie]

yeah that strat is really nice!!  The marykay is great too!!  Really top quality work. 

HOw did you do that aged fingerbaord finish?   

> SNIP

I never played a total vintage neck, i heard they are hard to play on because of the small frets, but Jimi did it. 
But i just reviewed your post and see that you fixed it by using jumbo frets.

Thanks!
I aged the fretboard with a little bit of lacquer thinner on a Q Tip. Just rub the lacquer till it eats it away. (Won't work on Poly). Then rub in some pencil lead, charcoal, dirt, oil, grease, stain or whatever until you get the right effect. Don't try this on a good neck at first! It may take a few tries to get it right.

The 7 1/4" radius on a vintage neck does make it tougher to bend. The jumbos do help a lot, but I set my action high on purpose so I don't play too fast. I'm about to order a USACG neck for my next project. It'll have a 9 1/2" radius with jumbos. Bending will be easier on that.

Sorry to hijack the thread with non-stompbox talk!

[formerMember1]

hey guys,
I want to add the 1n34a ge diode ernie has so graciously sent me.  I want to add it to my Rangemaster.  From reading around, i found out i solder it to the emiiter to base of the germanium transistor,...right?

If so,.then where would i put the cathode(line) on the base or emitter?  I always get confused when people say reverse biased...

THe pedal is a Rangemaster, with a OC44 PNP ground.  (actually it is an austin treble blaster)

thanks for the replies , 
and thanks again 10acErnie

[bioroids]

As your circuit is PNP, you should put the diode with the line going to the emiter.

Reverse biased means that the cathode is more positive than the anode, so no current can flow (except the leakage)

Luck

Miguel

[formerMember1]

thanks bioroids 

[formerMember1]

bioroids:

My tranny is biased at 7.02volts.  When i add the ge diode, with the cathode to emitter and anode to base.  THe tranny changes it's biasing from 7.02volts to 7.53volts.   I can't have that change in biasing.  Is there a problem?  Or is that normal for the biasing to change when adding this diode?


thanks

PS:THere was another thread where someone had the same problem, but then they said that it was their mistake and it only drops the biasing very very minimal. 

[bioroids]

Do you have that voltage on the collector of the transistor?

I'm not really an expert in this, but I suspect that the diode can have an effect in the biasing.

That's not a problem anyway, if all parameters look normal (base and emitter voltage besides the collector) maybe you can alter the biasing resistors to get to the voltage you want.

Also before doing anything you should give it a little time. The transistor and the diode should be at the same temperature for the "compensation" to ocurr (and that is not probably the case right after soldering). I would mount them as close as posible too. Let it rest a few hours just to be sure and then measure again and adjust the bias to your taste.

I dont know any reason for it to not work (besides putting the diode backwards, wich would have a big effect in gain).

Luck!

Miguel

[formerMember1]

yeah 7.02 is on the collector.

I didn't solder the ge diode, i attached it via alligator clips.  The pedal is built on a terminal strip.  THere is virtually no room in there for the diode but i was gonna do my best.  THe biasing resistors are not going to be able to be changed since they are on the bottom of the terminal strip, and there is no way to get at them with a soldering iron.  Also the terminal strip is epoxy glued in there.

THe diode isn't backwards since i tried it that way, and the biasing changed to around 8.79volts or so.

I guess maybe i can't use the diode in this pedal.  And that really sucks becuase the pedal sounds awesome, my favorite pedal, but it really suffers from the Germaniumitis of sounding good one day and terrible another. 

Anyone else try the diode in a RM and have to change biaisng?

thanks for your help bioroids. 

When i figure out how to get my digital camera that is on my tape video camera to load pictures to computer, then post pictures here, you would see what i mean.

[bioroids]

Well, I dont remember if I had to change bias (did it on an easy face) but I suppose that was probably the case. Also I dont think it would work with the diode too far away from the transistor

Maybe you can use it as is, just try not to expose it to sunlight!

Or you can build it again with the diode in and a trimpot for biasing

Luck!

Miguel

[formerMember1]

thanks bioroids!! 

Well, see my pedal sounds good one day and not as good another.  It doesn't sound horrible on those "off" days, but muddier than normal, and not as trebly.  I think it is becuase of temp change, but everytime it doesn't sound right i check the biasing and it is fine, it never goes above 7.03volts or below 7.00volts  When ge trannys sound different from temp, doesn't the biasing change?  Or does the bias still read the same and the pedal just sounds different?

thanks

[bioroids]

When ge trannys sound different from temp, doesn't the biasing change?  Or does the bias still read the same and the pedal just sounds different?

I really don't know about that... that's a good question.

I'll search the forum, maybe someone answered this before. The article on the Plate-to-plate seite must have some info on this as well.

Luck

Miguel

[formerMember1]

this is what i found out on Phillips fuzzcentral site, it is under the axis face germanium pedal.

The biggest problem with the Germanium transistor version of the Fuzz Face circuit is that Germanium transistors aren't temperature stable like Silicon transistors. When the inside of the enclosure starts to heat up, whether it's from stage light or sunlight, the pedal will start to sound very bad, and eventually if it continues to heat up, it will stop working all together. This is called "thermal runaway." The best way to stop this problem is to add a reverse- biased Germanium diode across the base-emitter of Q1. This process is described in detail in the Britface article at the Plate-to-Plate effects site. Make a note that this problem only happens with Germanium transistors, and in order for this mod to work, the transistor AND diode have to be Germanium and the diode HAS to be reverse biased.. For a PNP circuit, the cathode of the diode would be connected to ground instead of the anode

He says for a PNP pedal run the anode to ground.  I wonder if this is what i should do in my Rangemaster?  The way i tried it was i connected the cathode to the emitter and the anode to the base. 
Maybe i should connect the cathode to emitter and the anode to ground instead of the anode to base?

Anyone know?    bioroids?

[bioroids]

Hi!

The diode has to be connected between base and emiter of the transistor for this to work.
Have you checked the Brit-face article linked in that page? It's pretty clear where the anode and cathode should go in the drawing there: the arrow of the diode goes in opposite direction than the arrow in the transistor (on the symbols I mean). So the line of the diode has to go to the emiter, and the other side to the anode.

Is easy to get confused with this (I feel a little dizzy right now )

Here's the link to the Brit-face article: http://www.geocities.com/SunsetStrip/Studio/2987/britface.html is a very interesting read in fact

Luck

Miguel

[formerMember1]

So the line of the diode has to go to the emiter, and the other side to the anode.

where does the anode go?

I read the britface article, a few times but confused about it.  When they say the emitter-base junction i thought they meant cathode to emitter and anode to base, but now i take it as cathode to emitter and anode to ground,...right?

I am sorry i am confused by this mod. 

The diode has to be connected between base and emiter of the transistor for this to work.

How do i connect the cathode between the base and emitter?
I am on a terminal strip and the emitter goes to 4th lug, the base to 3rd lug and the collector to the 2nd
lug. 

WHere is between the base and emitter?

sorry if i sound so stupid   

[GFR]

OK,

I am on a terminal strip and the emitter goes to 4th lug, base to 3rd lug and the collector to the 2nd

If it is a PNP transistor:

base to 3rd lug - so the diode's anode goes to 3rd lug.

emitter to 4th lug - so the diode's cathode (that's the terminal closer to the stripe in the body of the diode) goes to 4th lug.

like on the article:

http://www.geocities.com/SunsetStrip/Studio/2987/tempcomp.gif

This shouldn't change the bias too much (unless your diode is too leaky or you're at a extreme ambient temperature).

If you put it the other way (anode to 4th, cathode to 3rd) it will "lower the gain" and the bias  change will be large (useful if your transistor has too much gain).

[bioroids]

Probably my bad english confuses you more .

I am on a terminal strip and the emitter goes to 4th lug, the base to 3rd lug and the collector to the 2nd
lug. 

Then the cathode goes to the 4th lug and the anode to the 3rd lug.

On the britface, the emmiter is connected to ground, that's why he says connect the cathode to ground. I mean, in that circuit, ground and emmiter is the same point.

Miguel

PS: I tried breadboarding a simple germanium stage yesterday and the diode addition seems to alter the bias, so you have to rebias after setting the diode in (I'd wait a few hours to be sure they catch the same temp)

Oops: GRF posted while I was writing. But he's right on the spot!

[puretube]

clamp them together, mechanically/thermally (and add the white thermo-goop)

[formerMember1]

thanks that cleared it up!  My mistake was not knowing that the base and ground were the same thing in this pedal.   

I have been doing it the way you say, and your right, it does change the bias.  Unfortunatly the way the pedal is built i can't change the biasing.  But i will try it on my other Rangemasters i am going to build. 

thanks for the help you have given me,