LDR to TTL level

P

Panji

New Member

• May 11, 2003

• #1

:?:

I want to convert a lamp condition to TTL level using LDR. When the lamp is on the logic from circuit is high (+5V) and when it is off the logic is low (0v). How can I build this circuit ?

Any help is appreciated.

 

kinjalgp

Active Member

• May 12, 2003

• #2

Use a transistor.
Bias the transistor using Potential-Divider bias and use LDR as one of the arm of potential divider network. Use Vcc = 5V. Collector resistor = 10k. The output should be taken from collector.

 

P

Panji

New Member

• May 13, 2003

• #3

But... what type of transistor can i use ?

 

kinjalgp

Active Member

• May 13, 2003

• #4

Any general purpose NPN tarnsistor like BC547 / BC547 / 2N2222 etc.