Tuesday, October 4, 2022

12VDC to 3VDC

 Several years back, you guys and gals came through with answer to a, "What do you call it?" question.  

For those with less than eidetic memories, my goal was to replace the motor battery pack on the big reflector's equatorial table with the 12VDC battery pack I use for the more conventional Losmandy mounts.  I achieved my goal; a simple little box with as 12 VDC cigarette plug on one end and two wires carrying 3VDC on the other.  I never ended up doing the transplant because I could not see how to avoid a hopeless tangle as the mount turned on the azimuth axis.  

But I was suddenly inspired today, and I can see why that word "inspired" originally carried the idea that a god put the idea in your head.  I was not thinking about the problem at all; it just hit me like a bolt out of the blue (a very Zeus-like idea, by the way).  The tangling problem was from an attempt to replace the battery on an assembly up on the rocker assembly which goes 360 degrees, 720, ... over the course of a night.  The battery pack for the motor is always aimed south.  All the rotation is relative to it.  So I looked to see if the project box could be attached next to the battery pack bar on the Crossbow Equatorial Table.  Maybe hanging off the edge of the bottom plate of the table that holds the casters?  

Voila.  The transformer inside that project box is really small; it will fit into the place currently occupied by the battery pack.  While removing it from the project box the transformer, which was working yesterday, broke in a way that should not stop it from working, but it did.  They are only about $6, so I ordered another one.  I will put in place of the battery pack and no longer worrying about leaving the motor on, which means the next night I am chasing down AAA batteries.


  1. Technically, that is a DC-DC convertor. A transformer only works on AC.

    Internally, that uses a very small transformer and some surprisingly fancy electronics to make the DC into high-frequency AC, transform the voltage, then go back into DC. Amazingly, they are able to achieve above 90% efficiency doing this...

    1. I learn something new every day. Thanks.

    2. Wow. I would have never imagined it was that complicated. I thought changing DC voltage was about as complex as modifying the Neon bulbs we used to make AC continuity testers in Electric Shop: Carefully solder a resistor of a certain value onto the lead of a Neon bulb so it didn't POP when you plugged it into 120 volts.