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| Frequency counters operation |
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| Y2KEDDIE:
I’ve noticed some frequency counters, when no signal is applied to the input, the display reads all zero’s, as one would expect. Some counters display random readings, until a signal is applied, or the reset button is pressed. This is the case of a high resolution counter I bought from e-bay. The operation literature say’s Radom display is normal operation. Why do some counters require a manual reset and others don’t. |
| pcprogrammer:
Open input sensitive to noise? No proper power on reset in the circuit? |
| shakalnokturn:
I suppose it has something to do with the way they trigger and surrounding EMI. |
| xrunner:
--- Quote from: Y2KEDDIE on March 04, 2023, 04:12:54 pm ---I’ve noticed some frequency counters, when no signal is applied to the input, the display reads all zero’s, as one would expect. Some counters display random readings, until a signal is applied, or the reset button is pressed. This is the case of a high resolution counter I bought from e-bay. The operation literature say’s Radom display is normal operation. Why do some counters require a manual reset and others don’t. --- End quote --- If the input isn't terminated, then it's going to receive signals from the environment at the center pin of the input connector, however poor of an "antenna" that tiny piece of metal is. Now, they may be very small signals or they may not be - it depends on your local environment and the sensitivity of the unit. Try terminating with a 50 ohm termination and see if the random signals stop. |
| edpalmer42:
The other thing you can do to suppress the garbage displays is to move the trigger level slightly off zero. It won't affect a normal reading since the input will hopefully be at a much higher level. Note that this type of garbage display could be caused by either external signals or internal noise or a combination of both. Ed |
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