| ??? 01/16/05 12:52 Modified: 01/16/05 12:55 Read: times |
#85044 - No more than about 10kOhm Responding to: ???'s previous message |
Kalpak said:
If voltage source(0 to 10V) then the analog front end must have high input impedance,... But high input impedance is unsuited! Many analogue signal voltage drivers provide a source impedance of nearly zero Ohms. This is done by including an eventual output resistor inside the feedback loop. Such devices deliver current limiting, protection against overvoltages (surges, bursts, ESD), protection against instability caused by capacitive load AND zero Ohm output impedance. Such amplifiers are suited to drive loads down to 2kOhm or even less. To decrease susceptibility against noise, hum and RFI load impedance should not be much greater than 10kOhm. Mains operated unit "Caveat Emptor" about the isolation. To begin with check with a neon tester for leakage, that way even if things don't work, smoke is not generated. This is particularly true about compact SMPS based mains unit. A good digital volt meter (DVM) can withstand an overvoltage of about 1000VRMS. So, measuring impedance between signal ground and safety ground (green yellow wire of mains) should not result in any 'smoke'. Nevertheless, only Safety Class I and II specified devices should be handled in that way. Then, signal ground may even directly be touched without the risk of being injured! Kai |
| Topic | Author | Date |
| Source Impedance | 01/01/70 00:00 | |
| Re | 01/01/70 00:00 | |
| Impedance measurement | 01/01/70 00:00 | |
| Being more concrete | 01/01/70 00:00 | |
| What about my Rogowski Coils. | 01/01/70 00:00 | |
| Already answered in detail! | 01/01/70 00:00 | |
| Re: ' Detailed Answer' | 01/01/70 00:00 | |
| Bridge | 01/01/70 00:00 | |
| What Bridge, | 01/01/70 00:00 | |
| bridge | 01/01/70 00:00 | |
| and ... | 01/01/70 00:00 | |
| Using an OPamp | 01/01/70 00:00 | |
| Using OpAmp | 01/01/70 00:00 | |
| Some disadvantages | 01/01/70 00:00 | |
| Correct formula | 01/01/70 00:00 | |
| Thanks Kai, | 01/01/70 00:00 | |
| LCR meters quite common | 01/01/70 00:00 | |
Re: LCR Meter. | 01/01/70 00:00 | |
| Resonant coupling... | 01/01/70 00:00 | |
| Sorry! | 01/01/70 00:00 | |
| Go with the rule of Thumb | 01/01/70 00:00 | |
| No more than about 10kOhm | 01/01/70 00:00 | |
| Line drops | 01/01/70 00:00 | |
| Thicker cable | 01/01/70 00:00 | |
| Freq domain analysis | 01/01/70 00:00 | |
| re: Source Impedance and driver types | 01/01/70 00:00 | |
| universal solution | 01/01/70 00:00 | |
| Thanks .... | 01/01/70 00:00 |