How to design a ADC to 7-segment?

[xiaoxiao]

hi fellow guy/gal

i am new here... i am doing a Optical Pulse Detector which is to detector the pulse rate. then i having the problem to design the ADC which mean that my O.P.D output is an analog signal. which i need a A/D circuit to convert the analog to display at the 7 segment to detect how many pulse....

so i need help on how to design it?

hope u all can provide me the schematics of it or the link...

thousand thank to all of u.....

 

[Analog]

hi fellow guy/gal

i am new here... i am doing a Optical Pulse Detector which is to detector the pulse rate. then i having the problem to design the ADC which mean that my O.P.D output is an analog signal. which i need a A/D circuit to convert the analog to display at the 7 segment to detect how many pulse....

so i need help on how to design it?

hope u all can provide me the schematics of it or the link...

thousand thank to all of u.....

Seems odd that your pulse output is analog, why isn't it a digital signal? Can you post a schematic?

 

[Blueteeth]

Hi,

When you say 'optical pulse detector' what is the application? Do you mean 'heart beat pulse' like an ECG? You will only need an ADC if the voltage is of real concern, or if you wish to store the exact waveform. If you are simply looking for 'pulses' in the analogue signal, you don't need an ADC.

Well, technically a schmit trigger, or a TTL inverter IS an ADC, it just has a resolution of 1 bit.

For counting pulses, I would use a comparator, where you set a threshold so that the output is high ('1') when its over this threshold and low ('0') when its under. Alternatively, if there is some noise in your signal, use a schmitt trigger, or at least a comparator with hysteresis. Then what you need is a frequency counter, which detects the time between the pulses and outputs the results on your LED display.

I think we need more information to be of any use. What is the application? What is the max/min frequency of these 'pulses'?

Regards,

Blueteeth

 

[xiaoxiao]

as i using a MC602 op-amp to do out the pulse detector. as for the schematics i cant post it as i dun had the scanner to scan in.... but i can say that it detector our pulse/heart beat.


by the way comparator and frequency counter where can i find it and my circuit had only had one output which how to use a comparator to compare the voltage?

regard
xiaoxiao