EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: richmit on September 25, 2021, 07:43:18 pm
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A friend of mine has an old Yokogawa voltmeter on his bench. No power switch. No batteries. No ranges. Just pick up the probes and measure. That's pretty handy, and it got me thinking about an old Simpson 15-0-15 microamp meter I have on the shelf. In the distant past I put it to good use for low noise measurements, low impedance voltage measurement, and the occasional bridge. I still occasionally use it, but it would be perfect for building myself a lowish Z voltmeter.
(https://www.mitchr.me/SS/bof/anavoltmeter/20210925_142552_c_small.jpg)
I still wanted to be able to use the meter directly -- that's what the white post is for. I also frequently use the meter with a 10K, 10-turn pot in series -- that left most red post isn't a post at all, it is the knob for a long life pot. Using the center red post one gets the meter in series with that pot. Finally the top and bottom posts are the voltmeter ranges: -25 to 25V at 1 Mohm and -1 to 5V at 200 Kohm.
Anyhow, I it turned out well. It's very functional. Super easy to read -- it has a fat, high visibility needle. I have it mounted on a swing arm on the right side of my bench by my DMMs. Kinda adds some nice steampunkeyness (sp?) to the bench.
(https://www.mitchr.me/SS/bof/anavoltmeter/20210925_141941_small.jpg)
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Do you know what the resistance of the meter movement is and if it is diode-protected? If not, you might save yourself some heartache if you added diodes and maybe some series resistance so that the total meter resistance was at least 10k-ohms.
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Do you know what the resistance of the meter movement is and if it is diode-protected? If not, you might save yourself some heartache if you added diodes and maybe some series resistance so that the total meter resistance was at least 10k-ohms.
The meter is 1822 ohms, and is not internally diode protected. I had to add my own. I also put in a fuse. I doubt I'll ever trip it with the stuff I work on, but I figured better safe than sorry.
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Nice scope richmit. :)
What probes have your paired with it ?
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Nice scope richmit. :)
What probes have your paired with it ?
When I got the scope I had hoped to use my Cal Test CT3290RA (a clone of the Tek P6139A), but my scope's input capacitance is on the high end and those probes wouldn't compensate!!
So I have two sets of probes. The ones in the photo are the ones I use everyday -- 300MHz probemaster 4900s. When I need more bandwidth I use Keysight N2873A -- nice probes, but the longer, stiff cables make them annoying on a small bench -- accessories are also stupid expensive for them.
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Nice scope richmit. :)
What probes have your paired with it ?
When I got the scope I had hoped to use my Cal Test CT3290RA (a clone of the Tek P6139A), but my scope's input capacitance is on the high end and those probes wouldn't compensate!!
So I have two sets of probes. The ones in the photo are the ones I use everyday -- 300MHz probemaster 4900s. When I need more bandwidth I use Keysight N2873A -- nice probes, but the longer, stiff cables make them annoying on a small bench -- accessories are also stupid expensive for them.
OK thanks.
Got some of these 350 MHz 10x sense probes to characterize as they are very well priced:
http://www.pintek.com.tw/product_detail/landersound/index.php?Product_SN=26541&PHPSESSID=td1lilpk6h44lhdpd7mqk59lr7&Company_SN=6002&Product_Site_Classify_SN=17073 (http://www.pintek.com.tw/product_detail/landersound/index.php?Product_SN=26541&PHPSESSID=td1lilpk6h44lhdpd7mqk59lr7&Company_SN=6002&Product_Site_Classify_SN=17073)