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The input threshold voltages of a 74HC04 are very close to the output high and output low voltage at the output of the lousy old 741 opamps and the circuit might fail by itself or fail if the 74HC04 or an opamp are replaced.ruzfactor said:I have added a 74HC04 in the circuit and the MUX now works fine. But Will it be a problem later?
ruzfactor said:I have added a 74HC04 in the circuit and the MUX now works fine. But Will it be a problem later?
ruzfactor said:I will try to get one LM393. In the mean time I have think of something. Why cant I use a CMOS Inverter solve the problem?
One more thing, I have a LM324.
Its output voltage is 0.2V only when its output current is very low like the input of a Cmos IC. If it tries to drive the high current of a TTL gate then its output low voltage is very close to the TTL threshold voltage of 0.8V.ericgibbs said:hi,
The LM324 quad OPA has a Vout low of about 200mV, so it would be a better choice than the obsolete 741..
hi,ruzfactor said:It worked! LM393 gives almost zero output and it gives +2.45V on high at O/P.
That sounds like you did not use pullup resistors on the outputs of the LM393, as Eric suggested. Since the LM393 has open collector outputs, you are effectively letting the 151 inputs float to a logic high, which is poor practice. Use resistors in the range 4.7k to 10k (value not critical) from each 393 output to Vcc.ruzfactor said:It worked! LM393 gives almost zero output and it gives +2.45V on high at O/P.
ruzfactor said:hi Roff
Can you please suggest me what's the best combination of resistance and voltage for making the LEDs brighter? I have used six LED (transparent which emits red light) but the light is not bright enough. that's why my LFR is not working satisfactorily.
ruzfactor said:Here's a picture of how i placed the LEDs:
I have connected the LEDs with a common wire. The wire is connected to +6V with a 320ohm resistance (100 and 220 in series). Should I add more LEDs? I have run my LFR over a black surface with track made of white tape.