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PostPosted: Thu Sep 13, 2012 10:45 pm
by Marcelo Jorge
To make the receptor's television motor to be functional with a Nipkow disc that I built, according to the picture published in Camara Monitor chapter 17, that improved speed control. The thing is that it isn't functioning. I have changed all components by new ones and it sill does not work. The motor is 12V, 90 mA and it functions, when tuned directly, normally. As it is an important circuit to the control of the disc's velocity, I would be very thankful if you could help me!

PostPosted: Thu Sep 13, 2012 10:49 pm
by Marcelo Jorge

PostPosted: Fri Sep 14, 2012 2:04 am
by DrZarkov
The trick is: Pin 1 is not in the middle like on the circuit, on the actual IC it is the left one:

PostPosted: Fri Sep 14, 2012 1:00 pm
by Steve Anderson
A good point, and one not often, nor clearly mentioned, that a circuit diagram in no way represents the physical properties of the components involved unless explicitly stated. The shape, size, layout, colour...anything at all is not the fuction of a circuit diagram.

Often (as the good Dr. has above) there will be a pin-out of the devices used, but in more complex diagrams these are often omitted to save space and left to the user to find out the data. This simply involves downloading the datasheet for the device, Farnell, RS and many others provide those links within their own web-site of the device.

Alternatively a simple Google will turn up what you need, e.g. "LM358 datasheet", "BC548 datasheet". Omit suffixes too, search on LM317 not LM317D2T-TR

Or if you know the manufacturer (LMxxx is usually National Semiconductor for example, but second-sourced by many others) use this very useful link for semiconductors...

For the tube-heads amongst us (though most will know of this), there's this...

Steve A.