- on Power Supplies
- Published in issue 10/2003 on page 0
Power from a GoldCap
GoldCap capacitors offer an interesting alternative power source when compared to conventional disposable or even rechargeable batteries. They can be charged very rapidly and can also deliver a high peak output current. Their voltage rating however is quite low so a little electronic assistance is necessary to raise the output voltage to a more useful level.PP3 (6F22) type 9 V batteries are often used in small portable equipment that require very little current and may only be used intermittently. Under these conditions its often the case that the battery is flat just when you urgently need to use the equipment. NiCd rechargeable cells are not a good choice in these applications because their self-discharge characteristics are much worse than dry cells and often there is no charge left after a long time in storage.
Components IC1, R1 and R2 cause a rather too high discharge current of about 5 mA on the Goldcap battery. This can be prevented by an additional diode between the Goldcap and the LM317.