Step down transformer as a battery charger ?

No, NiCd batteries want to be charged with a current source and the voltage must be monitored for full charge, and then the current discontinued (it's a little more complicated than this). A simple voltage source will not do it and certainly not one less than the battery voltage. Get a proper charger or something bad is going to happen.

Those are the maximum ratings.

"Mint"

Sounds like it is not.

.... Phil

Yes, assuming it is a _transformer_ and not a DC supply. Here's a simple "14 hour" type charger that will automaticaly reduce the charge rate from C/10 while the pack is below 11.2V to about C/80 when it reaches 11.2V. That will keep the pack topped off, but won't overcharge it. The circuit uses an LM317 adjustable voltage regulator to set the current, and a TL431 as a "programmable zener" to reduce the charge rate when the pack is fully charged.

----- 9VAC --->|---+---in|LM317|out---+ | ----- | | adj [15R] + | | | [100uF] +---+-----+-------+ | | | | | | | [470R] | | | | | [220R] | | | [LED] | | | | | | | | + N +-----+ | | i __|__/ | | C / / \ \ | d /431\---->/ 10K pot | | --- \ | | | | 9VAC----------+--------+---------+-------+

The 15 ohm resistor sets the current through the LM317 to 80 mA, which is the correct 14 hour charge rate for an 800 mAH NiCd pack. Set the 10K pot so that the TL431 draws current and the LED lights when the voltage measured across the NiCd reaches 11.2 volts. That will "steer" the charging current to about 50 mA through the 220 ohm resistor, and about 20 mA through the LED and 470 ohm resistor, leaving about 10 mA throught the pack, which is too small to harm it. The 100 uF cap shown can really be most any value between say 10 and 220 uF, but make it at least 16 volts.

Ed

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Power injector for use with 10 dB in line amplifier

Actual output without a load is around 13.5 volts.

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Class 2 transformer RoHS Adaptor

Input 120 V 60 Hz 65 mA

Output of 14.0 v at no load

Andy

None of the DC transformers I've tried have ever, ever worked. Not even with new batteries. I think it's because they are communist Chinese manufactured.

mike