PNP Rangemaster w/Charge Pump

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PNP Rangemaster w/Charge Pump

rocket88
Administrator
not so much a problem, but i don't know if anyone would see my comment on the main site. i just built a rangemaster with a charge pump, and as the volume goes up so does the typical white noise/hum. now i noticed Javi said that the 7660s can do that when used with germaniums, but i only noticed that until i was done building the pedal and noticed the noise. i didn't add the cap switch, and have been playing around with different transistors, and currently put in a GT109e with 307hfe and 0 leakage. when i put lower gain transistors in the white noise is there, but not as noticeable, and there isn't as much volume and gain.

i'm not sure if anyone figured out a way to help cure this problem, as it's awesome to have a rangemaster you can daisychain. i remember Javi mentioning in a thread that you can add a 47r-100r resistor from +9V to ground, but not sure if this will work in this situation since the pedal is PNP, so would i want to add the resistor from -9V to ground after the charge pump? also, mark made the comment about trying a different ic for the change pump, i think it was an LT1054, can i just swap it in place of the 7660s?

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Re: PNP Rangemaster w/Charge Pump

IvIark
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No not a 47R or 100R between supply and ground, it needs to be inline with the supply.  So you could connect the 9V supply wire to a 100R and the other end of the 100R to where the supply wire is supposed to connect to the board.

Try using a battery and cutting the charge pump out altogether.  So ground will connect to Boost 1 and 9V will connect to ground.  That will at least tell you if it is the charge pump or something else causing the noise.
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Re: PNP Rangemaster w/Charge Pump

rocket88
Administrator
well i have some good news. i swapped out the transistor for another type, and the noise is gone. it seems that the gt109's, while there are great gains with little to no leakage, and they are teeny tiny, they are on the noisier side. which is a real shame, cause they sound great and i have them with gains over 300hfe 0 leakage, hell i have one that tested using my dca55 and the ge tester from the sight has over 600hfe!! i have to find a way to quell the noise of them, cause they are great in tight spots, and sound good too.