With the old font, you need some componentes:
- 15K Resistor;
- 680R resistor (for led);
- 10K potenciometer or trim-pot;
And conector an clips for the power charger.
To make de caherger you need to wel de trim pot (or potenciometer) in the pin 1 of the 494 (or equivalent) and the 15K resistor in line witch the genative.
Then adjust to 13,8 volts and your charger is OK.
If don't can 13,8 Volts, you can try change the 15K resistor for an of 10K.
Is the best way to be a ecologic person, reuse an old font....
See the vídeo for more details (in portuguese...)