Snowman
New Member
Hi,
I need advice on a circuit:
1) Description of current setup:
* I have simple light detectors using some passive components and photodiodes whose output is fed into 7414s to clean the signal up. The result is a TTL level 1 or 0 in response to dark and light conditions on the sensor, respectively.
* I have 3 x 7-segment LED displays that are driven by chained
7490s and decoders - 7448s. All that is required to set the number is a serial set of pulses into the clock input of the first 7490 in the chain. This is NOT a rigid requirement of my circuit - just the way things are set up right now.
2) Problems and required advice:
* I would like to be able to count and display the number of darkend sensors - real time - on the LED display
* There are 150 sensors
* Sensors are spread out over a 1 meter (3.3ft) long surface
*I am concerned with form-factor of the final circuit for so many sensors
and realise that there are CPLD or PIC solutions that could accomodate this problem with more ease. But at this stage, I would like to implement the circuit with "off-the-shelf" TTL and passive components.
Thank you for any help in advance!
**PLEASE USE THIS EMAIL ADDRESS INSTEAD:**
ynospamavitalp@rogers.com
(remove the letter that sounds like "wye" and the words "nospam" to
get actual email)
Avital
I need advice on a circuit:
1) Description of current setup:
* I have simple light detectors using some passive components and photodiodes whose output is fed into 7414s to clean the signal up. The result is a TTL level 1 or 0 in response to dark and light conditions on the sensor, respectively.
* I have 3 x 7-segment LED displays that are driven by chained
7490s and decoders - 7448s. All that is required to set the number is a serial set of pulses into the clock input of the first 7490 in the chain. This is NOT a rigid requirement of my circuit - just the way things are set up right now.
2) Problems and required advice:
* I would like to be able to count and display the number of darkend sensors - real time - on the LED display
* There are 150 sensors
* Sensors are spread out over a 1 meter (3.3ft) long surface
*I am concerned with form-factor of the final circuit for so many sensors
and realise that there are CPLD or PIC solutions that could accomodate this problem with more ease. But at this stage, I would like to implement the circuit with "off-the-shelf" TTL and passive components.
Thank you for any help in advance!
**PLEASE USE THIS EMAIL ADDRESS INSTEAD:**
ynospamavitalp@rogers.com
(remove the letter that sounds like "wye" and the words "nospam" to
get actual email)
Avital