mvs sarma said:Remove R3 and rest of circuit functions. go for functional tests of ESR measurement .
RadioRon said:There is one other thing that might cause error in your measurement. That is that since the analog multimeter is probably a very high resistance, the time required for voltage to bleed off of C6 may be too large. .
RadioRon said:The value of 2.15 V at the transistor collector also seems to be good. However, this assumes that you have a capacitor across the test terminals TP1 and TP2. If you don't then this voltage is not correct. I will assume that you have a good capacitor there. .
Yes, these buffer amps are limiting amplifiers. Their job is to drive a 5 volt square wave into a low resistance load with enough current. They also isolate the oscillator from this load too. The original designer decided to use 5 of these amplifiers simply because that is how many he had available. It would be better if you had all 5 operating correctly but you can get away with losing one. The value of R2 to R6, 680 ohms is designed assuming 5 amplifiers so technically we should adjust the value. I suggest that you get IC1F working instead.whiz115 said:why it is not needed?!
also do you know what these "buffer amps" are?
do they amplify the output from the relaxation oscillator and seperate the
oscillator from the rest of the circuit?
whiz115 said:this time i was using my digital multimeter...
no i don't have any capacitor connected...
P.S did you noticed that i'm not getting anything on R7-R8 this is normal?!
whiz115 said:without using the probe we made.. i can see ~220mV from the esr meter output...R18 is 980K
i'm doing something wrong... i don't understand what's going on with the circuit and behaves so weird!
RadioRon said:Let's be sure that we aren't having problems because your meter at the output has very high resistance. Place a 100K ohm resistor (anything from 10K to 100K is ok) across C6 and then tell us what the output is once more.
whiz115 said:across means parallel?! if i put the 100k (98,5k) resistor parallel with the C6 i get 18.5mV at the output.
If i remove R3 doesn't help on anything.
with disconnected C3 the output is still 220mV
with disconnected C2 and C3 the output remains 220mV
If i connect C3 and let C2 disconnected the output is still high.
Btw.. i have a question! why one of these amplifiers doesn't work? i don't get it, is it burned?! if yes how come only one of them while they all are connected togather?!
whiz115 said:Hi
i can't understand what's going on, i think that if i disconnect C3 then i shouldn't be able to see any output! if this is true then it's ridiculous what is happening here
i'm checking all the time the PCB for bridges but i don't see any!
what should i do?
RadioRon said:However, we don't know if pin 5 is actually getting the signal. One way to check this is to use your digital voltmeter to measure resistance in ohms and, with the power removed from your board, measure resistance from the IC lead pin 5 (right where the leg goes into the black plastic of the ic, not underneath where it is soldered) back to the ic lead pin 2. It should be very low resistance.
Next, measure from the IC leg pin 6 (where the leg goes into the plastic, not underneath) to the junction of R7 and R18. You should see 680 ohms. Also measure from IC leg pin 6 to ground. You should see about 690 ohms.
RadioRon said:So, if you will be using a volt meter for this ESR device, then add a 10 K ohm resistor in parallel with C6. You mentioned that when you added a 100K ohm resistor at that point, the reading on the voltmeter went down to 18.5 mV. This is good. With no connection of a capacitor or short circuit across TP1 to TP2, we expect to see zero or nearly zero on the meter. 18.5 mV is nearly zero.
Then, when you short TP1 to TP2 with a capacitor or simply with wire, the reading on your meter should go up to some higher voltage. Please let us know what that voltage is. I expect it to be 0.7 volts.
whiz115 said:pin 2-5 resistance is infinite!!
pin #6 to R7 is 690ohm
pin #6 to R18 is 680ohm
pin #6 to ground is 690ohm
yes... i'm going to use the esr meter with a analog voltmeter... but for the above you said i'll try with the digital so i can see if it is going to be 0.7V
whiz115 said:Vcc ~5.80V
resistor 9.87k
output without resistor ~244mV
nothing connected 2.1mV
with capacitor 2.2mV
bridged 2.4mV
RadioRon said:We need to be sure that the circuitry from C3 to the meter itself is all working correctly now and I think the best way to do that is to repeat what we did earlier, that is disconnect the left side of C3 and use this point, with a wire, to probe IC1D pin 2. If everything is correct, we should see about 1.6 volts DC or perhaps a bit more. Last time you measured, what was it, over 2 volts, so this time should be similar or a bit lower.
whiz115 said:i did once again the test but i used the 100k resistor and the results was
nothing connected 22.5mV
with capacitor 22.3mV
bridged 22.6mV
i must get a stabilized power supply...
probably the IC said "bye bye" to all of us.....
i measure 4.70V to pin #2 maybe i did an awkward move and it got burned... should i change IC?
RadioRon said:Hmmm, I wonder what is going on here? When you measure 4.70V at pin 2, do you mean using our circuit of C3 and the rest, or do you mean when you simply measure with your DC multimeter on the volts range?
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