| doanster |
Hey, I have a problem for you guys.
Right now, I am in the process of replacing the built-in NiCd batteries in my cordless drill with better NiMH batteries.
These new batteries will be located externally. Now, in that space where the NiCd batteries used to be, I need a voltage regulation circuit.
Basic Criteria:
Power Source: approx 4.8 to 6.0 VDC (from the batteries)
Output: approx 0.5x[input voltage] to 1x[input voltage] (VDC)
"User Input Selector": a SPDT switch connected to the pistol trigger of drill, or a new switch / potentiometer / etc attached to where the 'trigger safety' use to be.
Heat Dissipation: low enough so that no cooling devices are required (no heatsinks, no fans)
Price: must be reasonably cheaper than buying a new drill :)
Any suggestions? |
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| testlab |
| What is the current draw? |
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| dnsey |
| I don't think drills use a 'standard' voltage regulator. It's sometimes possible to hear them oscillating at a few kHz. I suspect it's a design giving higher torque at low speeds, but I've never investigated. |
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| Eva |
Drills usually employ PWM regulation with approx 400Hz to 800Hz oscillator frequency.
This means that each second is divided into 400 to 800 equal time slices and the full supply voltage is applied to the motor during an adjustable percentage of each of these time slices. |
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