Friday, December 7, 2012

Feeback and a few questions from a newbie technician from Nigeria

Hi Humphrey, 
I have successfully downloaded your eBook and I started reading it, it was very important especially for us beginners.

Glad to note you have finally got the eBook and thanks for the feedback.

 Secondly I have two question, first in solving power supply problem using chopper transistor, you talk about the voltage at the base of this transistor is -1.38v so can we see this voltage using digital multimeter and analog meter and where to set our meter in order to test this voltage. 

The voltage at the base of a transistor is supposed to range between  0.3 – 0.7  V dc,  when doing live test on this base voltage using my digital meter I got this voltage -1.38 VDC…now this is funny . This funny reading could be as a result of the meter being un-stable due to a lot of oscillations going on around this area especially if the system is working. If the power supply is not working (no oscillations going on) then you should be able to read the correct voltage here.

The rule of the dumb is that whenever I see a voltage at this point (base) more than 0.3(+ or -) I assume the voltage is present at the base.

The best meter for testing voltage is digital meter and to test this meter negative probe should be at the main capacitor (-ve) pin and the positive at the point you want to test.

Q2: By using series bulb current limiter, you said for big screen TV we shall use 150w and 75w, so can I use one bulb 200w? 

Correct…that is even better.

Regards Humphrey

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