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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#21
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On Wednesday, May 5, 2021 at 2:35:19 AM UTC-4, Lucifer wrote:
On Mon, 3 May 2021 10:04:50 -0400, Ralph Mowery wrote: In article , says... my signal generator outputs some wonky voltages unless you have a load resistor across the outputs. It's 600ohms in a box with 1" spacing banana plugs and receptacles. I could never figure out why that's not handled by a pushbotton. Also, make sure you don't have any knobs pulled out putting you in zoom mode. My signal generator has one of silly scope knobs too for some reason. Signal generators are designed to put out a certain voltage into a certain load. Think of them as having a signal generating source of zero impedance in series with a resistor. Any load will devide between the internal impedance and the load impedance. For RF generators there were two standards. One was an open circuit Or very high impedance) voltage and the other was for a 50 ohm load. My service monitor has a software setting to do either one. It is from the old analog cell phone days and 30 years ago the cost was about $ 50,000. When the cell phones went digital the service monitor was put out for surplus and are selling for under $ 1000 now on the used market. When using a scope you have to allow for the peak or peak to peak ratio to the RMS value of a sine wave. As mentioned before I don't recall the ratio as I seldom need it and the scope I have now will calculate it and put on the display. If your RMS meter shows abot 120 volts AC out of the wall socket a scope will show around 170 volts peak. My signal generator is an all valve (four) unit and it works from 5 Hz to 600 KHz. Use your laptop as an oscilloscope (app) -- https://www.instructables.com/Use-Yo...-Oscilloscope/ |
#22
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On Tuesday, May 11, 2021 at 5:48:49 PM UTC-4, bruce bowser wrote:
Use your laptop as an oscilloscope (app) -- https://www.instructables.com/Use-Yo...-Oscilloscope/ 20Hz to 20 KHz is barely usable for audio. There are cheap digital scope kits on Ebay. That article requires an app that sells for $10. Why not add a bit more and get something that actually works? https://www.ebay.com/itm/264678652376 is DC to 200 KHz and is under $20. My current scope is a Tektronix 2465A. It is four channel, and its -3dB point is 350 MHz. I got it for $189.42 on Ebay. |
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