Red Dot finder power supply

[citaylor]

Hello. Once again I've gone out for an evenings observing only to find I left my red dot finder on, and the battery is flat. Because it uses a CR2032 3V watch battery, would I be able to convert it to using twin rechargeable AA batteries ? My dismantling and soldering skills are fine, but I know very little about basic electronics. Its only a cheap one, but I don't really want to blow it for the sake of just asking a question on the forums.

Thanks in advance...

[Stargazer51N]

Hi Chris,

You can replace your Cr2032 with two AA's connected in series but there are a couple of things you have to bear in mind.

1) there will be a resistor (cylindrical device with coloured bands and a wire coming out of each end) connected in series with the existing battery. This may be tucked out of the way either right next to the LED or in the battery cover. This stops too much current going through the LED. You must not remove this from the circuit, but you may need to replace it with one of a lower value because ....

2) the voltage supplied by two rechargeable AA's is 2.4v as opposed to the cr2304 which is 3v. The LED will come on but it may be 1/2 as bright as it was before.

[yesyes]

Also, be extremely careful with these button cell batteries. Don't even think about soldering wires on an old one. They explode. I've seen one leaving a nasty mark on a metal fire door.

[todd8137]

TBH i would chuck the red dot finder in the bin they are useless

[Gina]

That's virtually what I did with mine! I use a finderscope instead.

[todd8137]

That's virtually what I did with mine! I use a finderscope instead.

I brought a spare base for the telrad and when my 90mm frac came I did put mine in the bin

[citaylor]

I have a finderscope as well, but I find the red dot finder useful for the guidescope as it is quite difficult to look through a finderscope whilst moving the guidescope to a suitable "bright" star - it is quick and I dont have to be too precise.

Thanks to Stargazer51 & yesyes for their electronics advice...