The component overlay modded file is attached for plastic 2N2222whiz115 said:Resistors are fine...it's just that the three first are placed backwards than the rest two and look like their values are different. The transistor is a 2n2222emitter is placed down (where the white resistor is)
also the joints in the back side look awful...they aren't that awful the photos i uploaded are bad quality that's why they look like oxidized...
it would be much of a help if someone can tell me what to measure and what to expect...
specificaly about the transistor, i measure nothing between base-emitter... (it is possible i might not be able
to measure the transistor, because i'm not sure if my digital multimeter can deal with so small values of AC)
I think that the DC voltages at the transistor are approximately correct so it seems that the transistor bias is good enough. But I am wondering why you measure AC voltage using the 200VAC range on your meter? Why don't you measure with a lower range, like 10VAC for example? The measurement of "00.7" is encouraging and may indicate this is working OK.whiz115 said:i had the following results
VCC=5.70V
base-emitter: 610mV DC and when i turned the multimeter at 200VAC range
it shows "00.7". If i probe base and (-) of power source i see 770mV DC
Where the 680ohm resistors are if i probe between resistor-IC pin and the (-) of my power source i measure 5.50V DC but when i turned the multimeter to 200VAC then i see 11.2 (probably mV) resistors #2 from the top shows nothing.
RadioRon said:This would be so easy if you had an oscilloscope that you could borrow, but without that, we can try some more things.
RadioRon said:Let's follow a logical approach to the debugging process. First we want to be certain that the meter is not faulty.
RadioRon said:If the meter passes this test, then we can re-attach it to your circuit board. Next, we can follow the advice of eblc1388 in his post where he shows how to use the meter plus the rectifier bridge circuit to create an AC voltage probe. I recommend that you follow his diagram, and then use this probe to measure the AC voltage at the output of the oscillator.
RadioRon said:But I am wondering why you measure AC voltage using the 200VAC range on your meter? Why don't you measure with a lower range, like 10VAC for example?
RadioRon said:I also want to add this comment: do not despair. With patience and knowledge we will find your circuit fault.
whiz115 said:some more details to add...
it draws ~30mA from the source...
from the output i can measure ~260mV/2uA
This seems good, so the meter is OK.whiz115 said:with VCC=6.53V
resistor=467K
the current is 13,8uA
...
The X is a point where you need to break open the circuit. This would be done by unsoldering the left hand lead of C3 and letting it float in space. Then you would connect a piece of wire to this floating lead of C3 and the other end of the wire becomes your test probe. By doing this, you create an AC voltmeter out of your 50uA meter plus R17, C6, D1-4 and C3. We will use this AC voltmeter to check the rest of the circuit. However, we must add one more component to make it work. We must add some resistance in series with the 10K resistor R17. This is because the meter I assume you are using is a 50uA meter but with only a 10K ohm value at R17 we will have too much current flowing into the meter during our probing so we need to reduce the circuit sensitivity. We do this by adding your 467K resistor (even better would be a value between 75K and 270K, like 100K would be very good) in series with R17. This is temporary. Once we get everything working this will be removed.whiz115 said:The diagram is not 100% clear to me.. i understand that the dots are the places which i should measure, but the "X" is what? it's the steady point?! and why he shows the circuit broken next to the "X"?
also explain a bit what exactly you mean by saying AC voltage probe? you want me to use a diode in one of the multimeter's probe so i can make half rectification of the AC signal?
...
whiz115 said:because the lowest range is 200VAC and the highest 600VAC... it's not auto-ranging and i don't know if it can pickup frequencies of 150KHz.
this is my multimeter...
**broken link removed**
RadioRon said:AC voltmeter out of your 50uA meter plus R17, C6, D1-4 and C3. We will use this AC voltmeter to check the rest of the circuit. However, we must add one more component to make it work. We must add some resistance in series with the 10K resistor R17. This is because the meter I assume you are using is a 50uA meter but with only a 10K ohm value at R17 we will have too much current flowing into the meter during our probing so we need to reduce the circuit sensitivity.
An AC voltage probe is what we have just created and it is just another name for an AC voltmeter. It is simply an "envelope detector" followed by a DC meter. Our envelope detector is made up of the bridge rectifiers D1 to D4 plus C6. This turns AC into DC and works at your high frequency of 160 KHz.
whiz115 said:i haven't used any resistors or anything else because the output of the esr meter is connected to an analog multimeter and i have choosed the smallest range...
pin #2: 5mA
R2: ~4.3mA
R3:
R4: ~4.3mA
R5: ~4.3mA
R6: ~4.3mA
R7:
R8:
transistor collector: ~3mA
whiz115 said:lol....i hope i didn't burned anything!
pin #2: ~3.08V
R2: ~2.88V
R3:
R4: ~2.88V
R5: ~2.88V
R6: ~2.88V
R7:
R8:
transistor collector: ~2.15V
P.S note that my power supply is not stabillized and as you understand values aren't exact...
have a good dinner!
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