markmokris
New member
I have built the EXACT project documented in the FreqCount tutorial.
https://www.pjrc.com/teensy/td_libs_FreqCount.html
I have followed this exactly in every way. I am using it with the same preamp transistor 2N3904 and the same Schmidt trigger. I feed the circuit with a signal generator that is supplying the input to the preamp with about .6 vpp sine wave.
Except I am using a Teensy 3.2. I would like to use this frequency counter up to about 20 MHZ.
It works great up until about 10MHZ. After that the readings in the serial monitor begin to show low by a few KHZ. As I move the frequency up to 15MHZ, the readings are low by more - low by close to 12 KHZ. The higher I go, the more they are off.
I am using a 1000 msec gate time just like in the tutorial.
I am comparing the readings to 2 other, manufactured, frequency counters that agree with each other.
Is there something about the input stage that could be limiting my effective max frequency? Shouldn't the Teensy 3.2 permit me to count much higher than 10 MhZ with accuracy?
What might I be doing incorrectly? Any advice is appreciated.
Thanks,
Mark
https://www.pjrc.com/teensy/td_libs_FreqCount.html
I have followed this exactly in every way. I am using it with the same preamp transistor 2N3904 and the same Schmidt trigger. I feed the circuit with a signal generator that is supplying the input to the preamp with about .6 vpp sine wave.
Except I am using a Teensy 3.2. I would like to use this frequency counter up to about 20 MHZ.
It works great up until about 10MHZ. After that the readings in the serial monitor begin to show low by a few KHZ. As I move the frequency up to 15MHZ, the readings are low by more - low by close to 12 KHZ. The higher I go, the more they are off.
I am using a 1000 msec gate time just like in the tutorial.
I am comparing the readings to 2 other, manufactured, frequency counters that agree with each other.
Is there something about the input stage that could be limiting my effective max frequency? Shouldn't the Teensy 3.2 permit me to count much higher than 10 MhZ with accuracy?
What might I be doing incorrectly? Any advice is appreciated.
Thanks,
Mark