Yeah, Doug has the idea I was trying to express....ONE meter, with the inputs scaled to fit on the one meter range is clearly the cheapest, unless the meter includes the switching. But even if it did, that won't connect it to the right points, so you still need a switch.
Anyway, a DC meter will obviously read your DC. With a rectifier and some scaling, it will read your AC, so long as the waveform is decently sinusoidal.
You have a shot at reading frequency by combining the AC reading circuit with a resistor-capacitor filter, so that ther is a change in the voltage when frequency changes. You need more than one section of filter, and you won't get a direct Hz reading. You CAN likely get a sort of "percent error" reading, scale it for a "1" at right freq, and let it go above and below "1" with changes.
There are ways to get it to read actual Hz, but they add considerable cost, and aren't overly accurate with a voltmeter as the readout.
Current is a problem, as the range needs to be very low to use the 50 mV type shunt. You really need an amplifier circuit to boost it "on-scale" for your meter.
The idea is you switch the one meter input to the various adapter circuits to get the readings.
AC/DC Volt/Current meter for generator?
Moderator: Harold_V
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mark_dingbaum
Re: AC/DC Volt/Current meter for generator?
thanks again! Great ideas.
The Red Lion product is very close to what I'd like to buy, but I suspect the prices are somewhat beyond my taste.
The little digital panel meter from the MPJA link looks quite promising and the price is right. Using this meter, the DC voltage measurement is 'free', the AC measurement could be very easy, the current measurements are do-able, and the frequency is quite a bit harder, but still do-able.
I really appreciate the input, this forum has some of the most helpful, knowledgeable, and diverse people that I've ever 'met'.
best regards,
mark
The Red Lion product is very close to what I'd like to buy, but I suspect the prices are somewhat beyond my taste.
The little digital panel meter from the MPJA link looks quite promising and the price is right. Using this meter, the DC voltage measurement is 'free', the AC measurement could be very easy, the current measurements are do-able, and the frequency is quite a bit harder, but still do-able.
I really appreciate the input, this forum has some of the most helpful, knowledgeable, and diverse people that I've ever 'met'.
best regards,
mark
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J_Tiers
Re: AC/DC Volt/Current meter for generator?
I had a little time today, and so I used the circuit simulator program at work to see what could be done with a frequency meter using a DC voltmeter with a high input impedance.
Simulator indicates that with about 6 passive parts you can get a difference of 10mV per Hz, so 10mV difference from 59 to 60 Hz, or from 60 to 61 Hz. Output is on-scale for a low voltage meter, about 4 volts DC.
That should be enough to give a frequency reading of the "percent off" type, slightly more complex setups could improve the sensitivity.
Simulator indicates that with about 6 passive parts you can get a difference of 10mV per Hz, so 10mV difference from 59 to 60 Hz, or from 60 to 61 Hz. Output is on-scale for a low voltage meter, about 4 volts DC.
That should be enough to give a frequency reading of the "percent off" type, slightly more complex setups could improve the sensitivity.