At 10:16 PM 7/26/2010, Peter Loron wrote: >I have several clamp-on current probes that I'm trying to figure=20 >out. They have a screw-on connector that looks a bit like an XLR=20 >connector. There are 4 pins arranged in an arc across maybe 1/3 of=20 >the circumference of the connector. > >I'm familiar with the 2-pin probes or plain current sense=20 >transformers, but I'm not sure what to make of this one. > >These probes are SPX brand, but I have been unable to track down any=20 >further information about them. Presumably they go into some kind of=20 >automotive diagnostic tool. Your timing is impeccable . I purchased what I think are 4 identical current probes from eBay a=20 couple of weeks ago and have not yet gotten around to checking them out. Mine have a label on the side that says SPC Amp Probe 534-07097 and=20 a serial number. Anyway, the connector on my units is a Tuchel connector - this is a=20 locking DIN connector. You can use a standard DIN connector of the=20 correct pin count without needing to worry about the locking ring. I see these connectors primarily on European equipment but=20 occasionally run into them on gear manufactured in North America. I=20 don't have a recent source of these connectors but perhaps the=20 correct name will guide you in the proper direction. Based on your photos, I suspect these are a DC current probe with a=20 hall-effect sensor bridge at the business end. That flex cable going=20 into the clamp head would be 4 conductors if I am correct. I'm=20 guessing that the upper frequency response is anywhere from several=20 KHz to several hundred KHz - but not likely to reach MHz. I'd be really interested in a copy of any info you work out on these=20 units - save me a bunch of time for when I do get around to playing=20 with them. A schematic of the that PCB would be particularly revealing. Hope this helps - and thanks! dwayne --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .