Recently got a job lot of mainly
components, assorted tat and a few others bits. These two were among them…
Any ideas what they are/do?
The latter seems to be a home brew
Honest answer is I don't know.
I don't think these are the usual types of devices you'd find in a standard Radio/TV workshop, the only tenuous link is the Rank connection to one device. The bottom unit, Rank Nucleonics, lab device?
The top one as you already suggest is home-brew, look at the god awful components (diodes/resistor?) on long legs! Who would construct like that! Look how they are all leaning over, potentially shorting to one another, I'd not power that up, in that state.
It's a shame @valvebloke does not visit us any longer, I'd lay odds on, he might have a good indication of the bottom device's function, considering his background.
The DC Amplifier is an interesting piece of test gear clearly aimed for laboratory use as it has settings for measuring very low input levels of current (x10^-12 amp) i.e. pico amps, and charge Q (x10^-10) possibly could be 0.1μC.
I suppose this could be regarded as an electrometer characterised by high sensitivity allow it to make voltage, current, and charge measurements which are not available on a standard DMM. For charge measurements the input impedance is extremely high so as not to discharge the source.
Keithley Instruments now owned by Tektronix published a guide to low level measurements that might be a useful introduction.
Rich
The DC Amplifier is an interesting piece of test gear clearly aimed for laboratory use as it has settings for measuring very low input levels of current (x10^-12 amp) i.e. pico amps, and charge Q (x10^-10) possibly could be 0.1μC.
I suppose this could be regarded as an electrometer characterised by high sensitivity allow it to make voltage, current, and charge measurements which are not available on a standard DMM. For charge measurements the input impedance is extremely high so as not to discharge the source.
Keithley Instruments now owned by Tektronix published a guide to low level measurements that might be a useful introduction.
Rich
Thanks for that, and you're exactly right.. Someone on facebook said:
"The DC Amplifier was a common thing before digital multimeters and a sort of "replacement" for galvanometers (the really sensitive ones could be very fragile). It allowed you to connect a sensor (a thermocouple, oxygen sensor, geiger tube) that give really low outputs (think along the lines of thousandth of a volt) and 'translate' that to an analogue display that could be read - the dial on the left. The rotary control adjusts the sensitivity of the amplifier - like the range selection on a multimeter. It was also likely calibrated annually by an instrument technician so it's readings were reliable and consistent."