The goal with this project was to make a tube-based headphone amp with a transistor output stage. There exists other designs out there, but I found no one that suited my requirements.
The design shall use 12AU7 preamp tubes
There must be enough clean headroom to drive my headphones to reasonable volumes.
The design must be powered by mains (230VAC)
The design must incorporate filtering of the power supply.
The design must run on 12VDC (I had a 230V-12V transformer that I initially wanted to use for this build).
Computer PSU’s are great for DIY projects! Power supply units adhering to the ATX standard will provide 5v, 12v and -12v, and usually lots of it! These PSU’s also include short circuit protection, so you dont have to worry about blowing up your power supply.
Manufacturers of rechargeable electronic devices have in most cases standarised the input voltage to 5V, hence made it possible to charge the device from an USB port. This makes life easier. One charger to rule them all! This project is basically a voltage regulator which can be supplied from 6-30V DC, and gives a steady output of 5V, up to 3A. The circuit also implements Apples non-standard method to inform the device charging how much current it may draw.
The goal of this project was to make a relatively small acoustic cigar box guitar that was easy to bring along on hikes, etc, and still be a guitar (i.e. not an ukulele). The result became quite alright 3-string cigar box guitar sporting a 50cm scale, making it rather compact.
Most guitar effect pedals can be supplied with 9V DC. The main feature for such a power supply is low noise. A battery will give no noise, but power from the AC grid can cause 50/100Hz hum, plus higher frequency noise from other peripherals connected to the same grid. This design provides 500mA of 9V DC with very low noise.
This guitar effect pedal is based on the Belton BTDR-2 brick, which digitally emulates a reverb tank. The rest of the circuit is just housekeeping to buffer the input signal, mix the wet/dry signal and provide +5v to the Belton brick. Continue reading Digital Reverb Effect Pedal→
My workshop is from time to time a tangle of cables. Somehow they never get the treatment they deserve, and usually ends up in a even more entangled coil on the floor. The solution was this wall mounted hanger. This is not my design, I have seen similar things in other workshops, but never figured out where to buy on, so I made my own instead. Continue reading Hanger for test cables→
This amplifier is a simple 5W guitar tube amplifier based around the Fender 5F1 Champ design. The circuit is modified to allow for an EL84 power tube. Continue reading Guitar tube amplifier→
A sine wave generator is extremely handy. I use it as input signal to music related circuits, so I can measure the output with an oscilloscope. This circuit is based on TL072 op-amps, but I’ll guess it will work with many other dual op-amps as well. Continue reading Sine wave generator→
To successfully hit you targets with a shotgun, it is vital that the stock of the gun fits exactly to the anatomy of the shooter. This way the gun will basically aim where you look (with some training, off course). This was not the case with my inherited over/under shotgun. The stock was too low, causing me to always shoot lower than I aimed. Continue reading Modifying shotgun stock→
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