Author Topic: first pedal project question?  (Read 341 times)

ALBATROS1234

first pedal project question?
« on: July 09, 2019, 06:14:21 PM »
hello guys have been a lurker for a couple years. i mainly build vacuum tube guitar amps, repair tube radios and old console record players.i have repaired solid state a digital electronics for close to 20 years. i have been wanting to build some pedals and have gathered a handful of components some that were making me itchy was a handful of germanium transistors 2n2431 types(ac128 close cousin) which i tried to build a fuzz face with, it didnt work breadboarded and i blew it off last year. so last week i decided to breadboard a rangemaster clone,simple easy one gain stage treble/booster. i built it and it worked fine first time i tryed it except there is a high pitched whine noise in the background. when i have the gain knob turned up its not really audible and definitely not when i am playing. as i turn the knob down the whine/squeal gets louder. it never gets super loud but i know its not supposed to be happening. i tryed changing the transistors for others of the same type and the problem is still there. i even soldered it together on a perfboard thinking maybe because it was breadboarded dah,dah,dah. nope still there. like i said when the gain is cranked its pretty much gone, and you cant hear it when playing but i cant use the knob to dial in lower gain without the whine in the background. i dont get it its 3 resistors,3 caps,a pot and a germanium it took all of 5 minutes to solder it up. i am powering it from a heathkit et-3100 which is a powered breadboard with adjustable dc voltage with a signal generator .i started with 9 volts but i tryed to vary the voltage because i thought perhaps there is too much or too little voltage? obviously when i got down to like 4 volts approx, it quit and turning up past 9 volts makes it louder. i even tryed to reverse the polarity of the dc voltage because this board can do that shit. it helped slightly. as i am sure most of you will know this is a pnp type so its grounded to + and fed - dc, but with this reversed from what you think it should be it is a bit less audible. i am confused, this is too simple to not work, and i "think" i am doing it right. but it is my 1st pedal build sooooo. any advice appreciated. thank you.

Ice-9

Re: first pedal project question?
« Reply #1 on: July 09, 2019, 06:17:38 PM »
It could be your power supply, try running it with a 9v battery to eliminate noise from the PSU. If your PSU is  aswitched mode supply it could be injecting noise.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !
Do me a lemon, that a poor IQ for a glass of water.

ALBATROS1234

Re: first pedal project question?
« Reply #2 on: July 09, 2019, 10:40:54 PM »
yea, i guess it could be, i will get a battery and rig it up. there no knowns here, i havent built anything on thisbreadboard box, just had it from a bit of gear i was given not too long ago which is another reason i figured i should try to build something with low voltage, that b+ can sting if youre not careful. i guess i figured if i posted here with the guys who do this stuff all the time someone might go "oh yea change the jigger mah job and the squeal goes away, its a common problem" but the power supply does make sense, what else could it be. theres literally nothing there,lol. at least not compared to building a clone of a vintage amp/ thanks for your reply

ALBATROS1234

Re: first pedal project question?
« Reply #3 on: July 11, 2019, 11:59:15 AM »
yea so a battery did the trick. for whatever reason the power supply in the powered breadboard introduced a high pitched whine in the background. i cant figure out why. i supposed when i  build stuff will have to ignore this until its put in the final form.