I'm looking at adding a low-cost variable power supply to my electronics hobby bench. After years of cobbling together LM317's and LM7805's, it's about time...
I've found a few options which I am unsure about.
- Multi-turn knobs for voltage and current adjustment (as opposed to pushbuttons and separate coarse/fine knobs)
- A power supply that can range from 0 volts on the low end instead of 1 or 1.2 volts
- A switch to turn on/off the load
- The supply shouldn't overshoot the target voltage when switched on
- It should have a separate mains earth ground terminal (to allow combining supplies)
- Prefer linear for less ripple and noise (though switching offers smaller size and cost for higher currents)
Of course some factors depend on the intended use, some depend on preference, and some depend on budget.
(My intended usage is primarily microcontroller projects (3.3V-5V, <1A), automation and control projects (solenoid, stepper motor, etc) (12-24V, <5A), and low voltage lighting projects (12-24V, <3A). Budget ideally < $300.)
I asked earlier about the last point, linear vs switching, in a previous question. Olin convinced me that the disadvantages of a switching supply are minor, and certainly for my application, make sense for budget, bench space, and other reasons.
To touch on the other points:
- Multi-turn pots must be preference. I think they are better than single-turn pots, but I would prefer coarse/fine adjustments (or direct-entry via buttons) over turning a knob multiple times to make a larger adjustments.
- I haven't needed to work on projects below 3.3 volts, but I am mindful of the pico-power AVR micros, which can run at 0.7V. Certainly a supply that can go below 1 volt would be useful for this.
- A load switch is nice, but not a deal-breaker.
- How essential is it to have separate earth ground? I don't think I need to combine power supplies.
I've found a few supplies that I like, but I can't commit because none meet all the criteria.
- BK Precision 1550, 1-36V 0-3A, $150. Concerns: Doesn't go below 1 volt. Uses up/down buttons for adjustment.
- Circuit Specialists CSI3005X5, 0-30V, 0-5A, $130. Concerns: Unfamiliar brand and low price. (quality issue?)
- BK Precision 1671A, 0-30V 0-5A, $220. Concerns: Unknown adjustment turns; no earth ground terminal.
Is there some other supply or brand that meets all of these requirements? What points (if any) above, are truly important?