Gary, I agree that the brass blocks you mention are OK for low frequencies, but they often use relatively long conductors so inductance could be a problem. Also a possible problem at higher frequencies is the added inductance introduced by the time you have run wires to these blocks.
My suggestion would be to use four terminal precision current sensing resistors wired as close to the pcb as possible. Such devices are available from Rhopoint in the UK and probably other companies in the US too. The resistance starts at 1 mohm, which is probably less than you'd get from hooking up a great big bass block. This solution is likely to be higher cost however. As always, you pays your money and takes your choice. Surface mount type: http://www.rhopoint.co.uk/components/RHPM/rhpm.htm Leaded type: http://www.rhopoint.co.uk/components/LORL/lorl.htm [I have no connection with the above company, other than I have used their products in the past.] Regards, Richard Hughes Safety Answers Limited www.safetyanswers.ltd.uk Gary McInturff wrote: > > I was wondering the same thing. You can get brass blocks that drop mV per > lots of amps linearly. They come in different sizes and offer almost no > impedance at DC or higher freq's. DVM's or O-scopes are hooked in > parallel > with the blocks and the small voltage drop monitored. They handle lots of > power and are pretty cheap. > Am I missing something (again?) > Gary > > -----Original Message----- > From: Price, Ed [mailto:[email protected]] > Sent: Tuesday, February 17, 2004 7:52 AM > To: 'EMC PSTC' > Subject: RE: DC Current Probes > > > > > >-----Original Message----- > >From: Finlayson Joseph-G3162C [mailto:[email protected]] > >Sent: Tuesday, February 17, 2004 5:54 AM > >To: 'EMC PSTC' > >Subject: DC Current Probes > > > > > > > >Group, > > > > I am looking to source a DC current probe to measure > >steady state as well as inrush currents for a modular chassis > >up to 100 Amps DC. > > > Joe: > > Do you REALLY need a current probe? Can't you do this with a resistive > shunt > and an oscilloscope, using either differential inputs or simply > floating the > scope? > > That said, some of the widest bandwidth current probes (like 3 dB down > at 5 > Hz, very flat response, 1% accuracy) are available from Pearson > Electronics: > http://www.pearsonelectronics.com/ . Unfortunately, I don't know of a 100 > Amp DC current sensor; all the Tek or HP probes (Hall effect or > magnetoresistive) that I've seen are limited to about 6 Amps or so. > > > Ed > > > Ed Price > [email protected] WB6WSN > NARTE Certified EMC Engineer & Technician > Electromagnetic Compatibility Lab > Cubic Defense Applications > San Diego, CA USA > 858-505-2780 (Voice) > 858-505-1583 (Fax) > Military & Avionics EMC Is Our Specialty > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ieee-pses.org/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ieee-pses.org/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
