gleaner~ post 16 and 21 contradict
No its not 100 percent verified and you acknowledge that yourself. Its also my concern and I've pointed out why in my posts. Considering the audio circuit went kaput well that just increases my desire to know the true layout of the circuit.
As to batteries: Well they can be cheap enough and you'll get what you pay for. I've made my own battery packs and regulated power supplies for the simple reason of extending the operation time of the detector in question. I've also made Lithium power supplies to cut down on weight. Its really all in what your aiming for and the author was looking at the operational time verses expenditure on new batteries. Its a great thing to play with and if you have a green streak its less wasteful.
Now gleaner makes a point that the size of the battery has no effect on power draw, ie amp draw, and this is true. However the thought is incomplete. Battery size does have a corresponding effect on how long the battery will maintain operational voltage level relative to how deep the batteries current capacity is.
The example of a bunch of 12 volt batteries in series with the output always being 12 volts is good however add to that one 12 volt battery will last 1 hour before the operational voltage drops below effective use on a given machine and that say 6 batteries will give 6 hours of life before dropping below effective voltage.
This is often seen in the physical size of a battery. But with new battery technologies its not always true anymore.
An 18 volt battery voltage regulated at 9 volts gives the overall effect of paralleling two 9 volt batteries as you are effectively halving total power draw as well as working down from a higher peak input power. The limiting factor at this point is the point of regulation~ are you using an IC regulator which will cut off below 9 volts, a zeiner diode regulator which will cut off at or just below 9 volts, or a simple power splitter using resistors which will continue to work till power is exhausted.
Another limiting factor will be that the 18 volt battery itself will have a dramatic drop off off output ampherage once it dips below a certain point as well. That's just because of the way the battery is built. As I said its an overall effect but one that is interesting to play with and in the end usually does not make any difference as long as the goal is made for what is desired from the power supply.
