Variable current/voltage limiter

Hi I'm in search of circuit which would limit maximal output current and maximal output voltage and which I could set with potentiometer (I need this to charge variable NiMh batteries). Bare in mind that input to this circuit will be from solar panel, so the input voltage and current could be very low. Does anybody know about these kind of circuit?

Sounds like a standard bench power supply circuit with a current limit to me.

There may be some examples on datasheets for variable linear regulators such as the LM317 - beware
though as there are both current-limit and current-foldback circuits, the foldback type is not what you
want I think. Google terms like "current limit variable linear regulator"

For solar charging efficiency can be important so a switching regulator might be best. How about something like this?

Russell.

russellz:
For solar charging efficiency can be important so a switching regulator might be best. How about something like this?

Russell.

Know about these ones, have one home, but the problem I'm facing is that all the regulators require some input voltage which is quite high considering I will have 6V solar panel so that's not exactly what I need. Input voltage of around 1-2 volts would be ok. I only need to be able to adjust maximal current and max. voltage going out of the solar panel (circuit).

considering I will have 6V solar panel

So kind of you to let us know this vital piece of information once we have wasted our time answering a false question.

Well, now you know at least what I'm after. So more info: maximal current solar panel can provide is 0,33 A. I need to limit max. current going out of the circuit to 260 mA and 3,8 volts.

Perhaps you should start by actually making some measurements of the solar panel in full sunlight, angled for maximum? Maximum current into a short circuit, current into a resistor dropping 3.8 V, and maximum open circuit voltage would help. The specifications of solar panels can be very optimistic.

Russell.

(I need this to charge variable NiMh batteries).

You're breaking the first rule of battery charging:

1- NEVER USE A CIRCUIT NOT DESIGNED TO BE A CHARGER TO CHARGE BATTERIES. USE ONLY CHARGING CIRCUITS (NOT REGULATORS OR POWER SUPPLIES).

In short, BUY A NiMh CHARGER. It's that simple. If you can't buy one , then make a NiMh charger.
(NOT A REGULATOR OR POWER SUPPLY !)

russellz:
Perhaps you should start by actually making some measurements of the solar panel in full sunlight, angled for maximum? Maximum current into a short circuit, current into a resistor dropping 3.8 V, and maximum open circuit voltage would help. The specifications of solar panels can be very optimistic.

Russell.

Specifications are for 1000W/m^2 irradiance with a standard spectrum, which is rather more than you
get at temperate lattitudes where the sun is never overhead. Power drops by at least an order of
magnitude if there is cloud obscuring the sun. A useful figure to have is the MPP voltage for 5% sun,
since this means you can get the best out of overcast sky. This is why typical "12V" PV panels output
19 to 20V open circuit in full sun - they have enough overhead to actually charge in cloudy skies.