74
Item nr.
| Production | The Netherlands, 1997. |
|---|---|
| Semi- conductors | Bridge rectifier, 7805 (stabilizer for DC). |
| Cabinet | Plastic. Size 37x11x25 cm. Weight 6kg. |
| Power | AC 230V, 10.6W idle. |
| Documents | Schema. |
The unit was produced from scrap computer parts. I used two power supply transformers, both with 28V of output, and use the second one to transform the output of the first back to line voltage. Its primary coils (now called the quarternary coils of course) can be switched between parallel and serial for either 110V or 220V of output. In its previous life, the plastc cabinet housed a 68000-based computer unit. Here is an inside view; apparently, in 1997 I didn't realise the importance of short leads yet.
The built in DC supply can be controlled from 6 to 11V, but by connecting an extra connector through a zener, I created a 2-7V supply as well. Due to transformer losses and the draw of the DC supply, the unit consumes over 10W of power when switched on.
| Obtained | 10/1997 from old computer parts. |
|---|---|
| Condition | 8. |
| Value (est.) | 6,8€. |
With some old semiconductor scrap I added a DC regulated power supply that can be controlled from 6 to 11V DC. In this way the unit also supplies transistorradios without the need to search the house for suitable batteries. 
In two decades, I blew the fuse two or three times, mostly by connecting defective radios on the AC out. With this little box taped to the back, I have spares at hand all the time. Nice machine, I never regretted building it. In December 2016, I installed a small digital panel meter to indicate the DC output. In 2025, after about 28 years of service, I replaced the power switch to match the voltage selector switch.
