Random Projects

This page contains some of the random home brew projects that I have worked on.

Kalamazoo Model 1 Tube Amp

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Kalamazoo Model 1 (B) Outside: Front After repair and cleaningKalamazoo Model 1 (B) Outside: Front After repair and cleaning This could be the cleanest (electronically) Kalamazoo amp that you'll ever see. The chassis is completely clean with not a spot of rust and the lettering is perfect. I'm afraid the knobs may not be original, as they are different than the other ones I've seen and the little blue indicator line on the knob seems out of place.  read more »

Gregory Apollo 800

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Tube guitar amp from the 60's. Tube lineup: 6CA4, 2x 12AX7 and 2x 6BQ5, 12" speaker combo. The speaker is a 12 inch Quam-Nichols ceramic speaker. All the Gregory amps came with this make of speaker. Actually sounds pretty good with a nice breakup when pushed. Some of this is probably due to the cathode biased class A output stage. Gregory Apollo 800 frontGregory Apollo 800 front Decent output at 10.5 Watts at 5% distortion. 12" speaker gives you good low end, but it's not very efficient, so it won't get super loud.  read more »

Hughes & Kettner Vortex Guitar Amp Head, 80 Watts

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Vortex Front: Hughes & Kettner VortexVortex Front: Hughes & Kettner Vortex Made in Germany, but so what? Pretty cheap bare bones construction: particle board cabinet that was cracked, needed glue and clamping, dowels that held the joints together had come apart due to lack of glue. The Korean spring reverb inside had fallen off due to cheap springs that held it to the chassis. The chassis itself was just a piece of rolled metal, not a box like the nice Fender chassis. Anyway, the amp came to me non functional and blowing fuses.  read more »

Upgrading a Linear Supply with a Current Meter

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I bought an Astron RS-20 on the cheap at the local hamfest for my radio. Only problem was the supply was lacking some basic features such as a panel meter for the load current and a banana jack on the front to make the supply output accessible. No problem, with a 200mV digital panel meter laying around, I knew exactly what I wanted to do...  read more »

Peavey JSX Mini Colossal

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Peavey JSX MiniPeavey JSX Mini This amp came to me with a very low output problem from a music store. All the power supply voltages were fine, but the output was low and it seemed like the amp was loaded down because the output transformer was fine. Since the amp was a "Power Soak" feature, I disconnect that to see it it was the issue. It was not. Upon futher disassembling the amp, it was apparent that the output wire from the output transformer was pinched. The power soak PCB was pinching the wire against the chassis. It was probably fine at the factory, but over a period of time and jostling around, it ended up a partial short. A little heat shrink tubing and re-routing the wire fixed things right away.

Then I went on to some mods...  read more »

Univox U65RN Fix

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Univox U65RN Front: No speaker, scratchy pots, intermittent jack.Univox U65RN Front: No speaker, scratchy pots, intermittent jack.

Made in Japan, this is actually a decent sounding solid state amp with decent reverb. The reverb tank is pretty small and it's located inside the chassis, so you won't see it from the outside. Amp didn't need much besides a good cleaning and a "new" speaker. I put an old Stromberg Carlson ceramic speaker (similar to a Jensen C12R) in there and that did the job nicely. The input jack was corroded and the connection to the chassis wasn't solid.  read more »

Cheap Orange Bass Practice Amp

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Orange Crush 20B Amp Front: Loose speaker connection.Orange Crush 20B Amp Front: Loose speaker connection.

This is a cheap bass amp. The original owner said there was no sound. Easy enough, once disassembled, it was obvious that the speaker connection came off the PCB. These quick connects are often loose and a quick clamp with a wrench can tighten them down. These quick connects are used in the Valve Juniors and Champs too.

Stereo Sleep Timer

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I wanted to be able to fall asleep listening to my stereo playing the radio, but I did not have a sleep timer fuction on my receiver, so I built this device to add sleep timer functionality to the stereo. The timer can be configured to run in two ranges: 99..1 seconds or 99..1 minutes.  read more »

Digital Thermometer with Memory

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This digital thermometer remembers the 12-hours high and low temperatures. This design uses a PIC microcontroller with a built in A/D converter. All the parts are tolerant to temperatures from -40 to 100 degrees Fahrenheit, so you can keep the device outside.  read more »

Laser Pattern Project

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I built a cheap laser pattern generator from stuff I found lying around my house and a few store bought items, I think I spent <$10. Here I am including the plans for the circuit and pictures of the finished project. Once upon a time I also took pictures of the patterns using a digital camera, but the shutter speed was too fast, so only part of the pattern was viewable.  read more »