Hi Lawrence, thanks I am starting to get the picture, I seem to remember doing this with a Wheatstone bridge in physics at school, but that was using massive rheostats and galvanometer and long ruler with wire. (I think)
Andy.
Your article is very interesting and after a few reads hopefully will fill in lots of gaps in my knowledge.
I am off to look for a pair of suitable phones, and to experiment with the voltage for the buzzer (reduce it from 9 volts to see when it stops buzzing) , as at the moment it is rather loud and accompanied with lots of arcing.
Just back from testing the voltage, and the buzzer sounds happy at 3v and the arcing is negligible, it seems to have bedded its self in and starts reliably now at 3v. the OP voltage goes up to 9vAC.
I have tested it with a 1k resistor and a .01uF cap and I can get a null in each case which seems to correspond to the setting on the dial, (give or take a factor of 10 or so)
At 3 volts the current draw is 100mA
I have a loudspeaker transformer connected to the phones socket and my bench speaker as the sounder. But the buzzer is very distracting in the background.
I am wondering if it was intended to measure resistances with DC and only switch in the buzzer for capacitors. I would think the battery drain would be significantly less if the buzzer was not operating on the resistor range.
thanks
Mike
Andy.
Your article is very interesting and after a few reads hopefully will fill in lots of gaps in my knowledge.
I am off to look for a pair of suitable phones, and to experiment with the voltage for the buzzer (reduce it from 9 volts to see when it stops buzzing) , as at the moment it is rather loud and accompanied with lots of arcing.
Just back from testing the voltage, and the buzzer sounds happy at 3v and the arcing is negligible, it seems to have bedded its self in and starts reliably now at 3v. the OP voltage goes up to 9vAC.
I have tested it with a 1k resistor and a .01uF cap and I can get a null in each case which seems to correspond to the setting on the dial, (give or take a factor of 10 or so)
At 3 volts the current draw is 100mA
I have a loudspeaker transformer connected to the phones socket and my bench speaker as the sounder. But the buzzer is very distracting in the background.
I am wondering if it was intended to measure resistances with DC and only switch in the buzzer for capacitors. I would think the battery drain would be significantly less if the buzzer was not operating on the resistor range.
thanks
Mike
