Author	[Modern View]
olilt 02-07-2013 13:14:26 68.56.185.101 Report to Moderator	I obtained a Simpson 150 Amp Clamp as part of an estate. The included instructions indicate that this tool was originally intended to be used with an analog AC instrument with a sensitivity of 5000 ohms per volt containing either a 2.5, 3, or 5 volt scale. There is a multiplication factor that is then used to calculate the total amps depending on the volt scale used. Can this tool be used with a digital multimeter? The scales on my meter are much broader that 2.5, 3, 5 volts AC. [Reply]   [No Email]
olilt 02-07-2013 19:31:52 68.56.185.101 Report to Moderator	Re: Simpson 150 Amp Clamp in reply to olilt, 02-07-2013 13:14:26   Ok, I'm beginning to get it. Just one clarification: should the resistor, or potentiometer be in series or parallel with the meter leads. Thanks for your response. [Reply]  [No Email]
tech4 02-08-2013 07:26:50 72.15.69.60 Report to Moderator	Re: Simpson 150 Amp Clamp in reply to olilt, 02-07-2013 19:31:52   Yes it should be in parallel. Or as suggested find a Simpson 260 or Triplett 630 or 310. The Simpson has a 2.5 volt scale and Triplett has the 3 volt scale. I still love my old Simpson 260 except when I need a precision measurement. I like to see that meter swing! [Reply]  [No Email]
MarkB_MI 02-08-2013 02:52:32 75.198.76.165 Report to Moderator	Re: Simpson 150 Amp Clamp in reply to olilt, 02-07-2013 19:31:52   The shunt is in parallel with the meter leads. You're lowering the input impedance of the multimeter so it looks like it's an analog voltmeter. If possible, get a precision (1%) resistor. Radio Shack resistors are typically 5%, which is enough to affect the accuracy of your readings. [Reply]  [No Email]
john *.?-!.* cub owner 02-07-2013 19:23:44 69.179.164.25 Report to Moderator	Re: Simpson 150 Amp Clamp in reply to olilt, 02-07-2013 13:14:26   The simplest thing would be to find an old Simpson 260 meter and use it. Or a better idea may be to go on Ebay and buy one of the new digital AC/DC amp clamps for around $25. [Reply]  [No Email]
olilt 02-07-2013 18:10:32 68.56.185.101 Report to Moderator	Re: Simpson 150 Amp Clamp in reply to olilt, 02-07-2013 13:14:26   I am getting lost in the discourse. Suppose I set my DVOM to the 2 volt scale. What do I need to do to? [Reply]  [No Email]
tech4 02-07-2013 18:54:25 72.15.69.60 Report to Moderator	Re: Simpson 150 Amp Clamp in reply to olilt, 02-07-2013 18:10:32   You will have to do some interpolation. Your digital meter should have a high input impedance and be a negligible load. You could use 2.5 as full scale but you would need a 12500 ohm resistor which is not common. 15000 is very common and you would use 3 volts as full scale. The scale on your digital meter should make no difference as long as it is above 3 that is 10 or 20 vac. For instance on the 300 amp scale the meter would read 3 volts or 200 amps will read 2 volts. On the red 12 amp scale the multiplier is 4 and 3 volts = 12 amps of 2 volts =8 amps and so on If I was doing it, I would use a 20K potentiometer and place across the meter leads and calibrate the reading to match the reading of a known good meter. [Reply]  [No Email]
Ted in NE-OH 02-07-2013 14:54:07 72.16.19.80 Report to Moderator	Re: Simpson 150 Amp Clamp in reply to olilt, 02-07-2013 13:14:26   Tech4 you are right, I stand corrected [Reply]  [No Email]
Ted in NE-OH 02-07-2013 13:59:19 72.16.19.80 Report to Moderator	Re: Simpson 150 Amp Clamp in reply to olilt, 02-07-2013 13:14:26   Yes, if you shunt the input to the DVM with a 5000 (5K) resistor. [Reply]  [No Email]
tech4 02-07-2013 14:23:00 72.15.69.60 Report to Moderator	Re: Simpson 150 Amp Clamp in reply to Ted in NE-OH, 02-07-2013 13:59:19   That is 5000 ohms per volt. To use the 3 volt scale you would need 3 X 5000 or 15000 ohms (15K) [Reply]  [No Email]