Crystal oscillator tester!! i need help

[gojjin]

i am building crystal tester project, i need to tests crystals up to the range of 33Mhz, however the frequency coming from the oscillator is incerted into the microcontroller were trought hte olgarithim it will output on the LCD the vale of the frequency.

now i build a simple oscillator and the output on the oscilloscope was shown however peak to peak voltage was 1V, all i need is amplify this signal so i would have 5V peak tp peak so it can be readable by the microcontroller, when i used LM358 and used ratio 10:1 on the output all i saw was gain in V but no sign of frequency output

can anyone help me with this issue

 

[MRCecil]

i am building crystal tester project, i need to tests crystals up to the range of 33Mhz, however the frequency coming from the oscillator is incerted into the microcontroller were trought hte olgarithim it will output on the LCD the vale of the frequency.

now i build a simple oscillator and the output on the oscilloscope was shown however peak to peak voltage was 1V, all i need is amplify this signal so i would have 5V peak tp peak so it can be readable by the microcontroller, when i used LM358 and used ratio 10:1 on the output all i saw was gain in V but no sign of frequency output

can anyone help me with this issue

The 358 you tried hits unity gain at about 1MHz, so it won't work for that application at 33MHz as you discovered. You can build an amp from discretes, but the simplest approach might be a high speed comparator if a square wave will work for you.

 

[crutschow]

How is the microcontroller going to read the 33MHz? Seems like you need a counter in front of the microcontroller.

 

[Hero999]

Use a high speed CMOS NAND/NOR/NOT gate with another gate on the output to buffer the signal.

 

[gojjin]

re:

can you help me how i am going to do this buffer... i have the design but i don`t know how to attach it here since it is calling for the URL

 

[Nigel Goodwin]

How is the microcontroller going to read the 33MHz? Seems like you need a counter in front of the microcontroller.

Not at all, a PIC will read over 50MHz, can't comment on other controllers though?.

 

[crutschow]

Not at all, a PIC will read over 50MHz, can't comment on other controllers though?.

Pardon my ignorance, but how does a PIC read the frequency? Does it have a counter function that you can input a signal and it outputs the frequency value? What is the resolution?

 

[Nigel Goodwin]

It's got a hardware counter that will accept over 50MHz, PIC frequency counters have been about for a LONG time, the original MicroChip application note used an OTP chip, but has since been converted to more modern devices, and LCD rather than LED displays.

Try looking here:

 

[Hero999]

can you help me how i am going to do this buffer... i have the design but i don`t know how to attach it here since it is calling for the URL

No designing it required, just add the gate to the output of the crystal oscillator.

To attach a schematic, go to advanced, click on manage attachments.