311
Item nr.
High voltage battery charger
| Production | The Netherlands, 2008.
Price was 1 Euro. |
|---|---|
| Semi- conductors | 3x 1N4007, zener diodes. |
| Cabinet | Plastic. |
| Power | AC 230V. |
To get a limit on the current, this charger uses a voltage that is much higher than the battery, namely 250V, and an 11k series resistor. Even when the power is shorted, current cannot exceed much more than 20mA. To get a limit on the voltage, a zener diode is connected over the voltage output. The zener is switchable, so that batteries of 9V, 54V, and 90V can be charged.
| Obtained | 5/2008 from home made. |
|---|---|
| Condition | 8. |
| Disposed | Storage (inquire if interested to buy). |
I used scrap parts as much as possible, only buying the diodes for about one euro. Diodes direct the transformer output, and load the smoothing cap of 8uF. Some "hum" in this power supply does not hurt me at all, but I want the charging process to continue all during the AC cycle. The loading current is limited by R1, and when power is switched off, the capacitor discharges through the bleeder resistor R2. So far, a low quality power supply is formed. R3 limits the current and the Zeners the voltage that goes to the battery. Some jacks allow the voltage over the battery to be measured during charging. A final diode prevents the battery from discharging through the bleeder, in case it is connected with the charger switched off.
The projects I built are usually electrically simple, but I always have trouble finding suitable cabinets for my thingies. Fortunately, shortly after the beginning of the twenty first century, floppy disks became obsolete, and I could use a plastic floppy disc box.
In 2014 I added a resistor, a capacitor and some wiring, to use the PlaatLader also as power supply for my Rex antenna. Or, for that matter, any other low-power tube device. DIN connector has mantle=black=ground, pin 1 blue is 6.3, pin 5 red is 250V.