The power supply has to provide, at a minimum, 0.7A @ +12V for the VL70m (power consumption measured at 0.6A @ 13.1V), and 1.3A @ +9V for the pitch-to-MIDI converters (GI-10: 0.26A @ 10.2V; GI-20: 0.8A @ 11.3V). Eventually, it will also provide bipolar power for the pre-amplifier (±12V or ±15V likely created using a charge pump converter).

Mains electricity is dropped down to 15V by a switched mode power supply (thus, I won’t have to work with 230V directly). The 15V supply is then regulated to 12V and 9V.

Quasar Electronics 3060 schematic (image copyright Quasar Electronics)

I use two 3060 kits from Quasar Electronics to provide 12V and 9V with the following changes:

• use the L78Sxx regulators (L78S12CV for the 12V supply, and L78S09CV for the 9V)
• use superbright LEDs (5.1kΩ current limiting resistor for the 12V supply, and 3.6kΩ for the 9V)

Additionally, I’ve modified the 9V supply as follows:

• replace WO2M bridge rectifier with a 2W01G to account for the greater current
• two heatsinks to help dissipate power (we’re dropping almost 3V @ 1.3A)