Dr Boogey Biasing question

[manis404]

Hi guys

I am about to finish my dr. boogey and that question has always been lingering on my mind. While turning the trimpots, at what point can I know that the jfets are correctly biased?

Thanks.

[alanlan]

I'm not exactly sure if there is a "correct" bias, but what I'd do is ground the input to the pedal, and then measure the drain of each JFET using a DMM and adjust for about 5 to 6V.  From there on in, you can adjust a certain amount to taste because the thing is, adjusting the bias on each stage actually changes the gain and therefore the sound as well.

[deadastronaut]

 i built two of these , in the gaussmarkov forum it recommends to bias them at 4.5v...seems ok with mine.....

[arma61]

Hi there

good infos in this tread

http://www.diystompboxes.com/smfforum/index.php?topic=76097.msg651125#msg651125


Armando

[DUY1337GUITAR]

I dont have a multimeter, it looks like im gonna have to take sometime to do this by ear...

[manis404]

Thanks everyone for your replies. Looks like the link Armando posted is the way to go. I'll keep you updated.

[alanlan]

I dont have a multimeter, it looks like im gonna have to take sometime to do this by ear...

Aw come on.  There is no excuse these days for not buying a DMM.  You're going to need one sooner or later and they are not that expensive these days.  I can buy one in my local "pound store" for about 2 or 3 quid.  Small, cheap and effective.  When you're really into it and can justify the expense buy a Fluke or something equally as good.

Would you paint a wall with your hands?  No, you'd buy a damn brush.

[DUY1337GUITAR]

I dont have a multimeter, it looks like im gonna have to take sometime to do this by ear...

Aw come on.  There is no excuse these days for not buying a DMM.  You're going to need one sooner or later and they are not that expensive these days.  I can buy one in my local "pound store" for about 2 or 3 quid.  Small, cheap and effective.  When you're really into it and can justify the expense buy a Fluke or something equally as good.

Would you paint a wall with your hands?  No, you'd buy a damn brush.

The cheapest I could fine is $17.  I got no money right now, just spent it on a new unibit, 9v adapter, and DR. Boogey parts.  I'm too busy with school to have a job XD.  I'll just be patient and get one within a couple weeks or so.

[alanlan]

Fair enough, found this though when you've got a bit of cash:
http://cgi.ebay.com/Digital-Multimeter-Meter-DMM-with-Probe-Test-Lead_W0QQitemZ180411633499QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item2a015f0f5b&_trksid=p3286.c0.m14#ht_3227wt_828

[oldrocker]

Believe I can see that money is tight especially these days.  A DMM is good to have and an audio probe.  An audio probe is cheap to make and IMHO is just as important as a DMM.  I recently picked up a capacitance meter kit for about $9.00.  I wish I would've had one of those when I first started building pedals.

[DUY1337GUITAR]

Fair enough, found this though when you've got a bit of cash:
http://cgi.ebay.com/Digital-Multimeter-Meter-DMM-with-Probe-Test-Lead_W0QQitemZ180411633499QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item2a015f0f5b&_trksid=p3286.c0.m14#ht_3227wt_828

oooooo $7 and free shipping.  Well I used the last $9 of my prepaid credit card for my unibit... So much to buy, so much to build, yet so much space in my wallet...

[alanlan]

If you happen to have an old moving coil movement (probably 100uA full scale type) knocking around in a bit of old equipment or find something at a garage sale or whatever, you can easily make your own volt meter.  Just needs a resistor:
http://en.wikipedia.org/wiki/Voltmeter#Analog_voltmeter

[burdt]

harbor freight tools always has super cheap multimeters. if there's one nearby go get one. they're always under $5