Showing posts from 2017

Very few things didn't work when I moved to Linux. Now there is one less...

There are things that couldn't work. There were things that I didn't need. Then there were applications or hardware that just didn't work, try as I might.
I still haven't got round to writing a driver module for my Microtek slide scanner. I kept a Windwoes 98 PC alive just to use it to scan slides.
Then there was the QX3 Intel microscope. This had nothing for Linux. It would only grudgingly work in Windows XP. When reading glasses and magnifying glass did not work, I would reach for the QX3. Only to find that I had put it on the top-most shelf. Out of reach...
Now I have a fully working QX3. With pictures of transistors and high precision voltage regulators. That I could not read satisfactorily with reading glasses and magnifier.
It is all thanks to the Linux community. Persistence pays off.
This only 10 times magnification. Makes them easy to identify, even when the paint is obscure.
The link? Sure! Here it is :-…

My serial port PIC programmer doesn't work!

It seems that the 'issue' that plagued us when NT4 came out is still with us. At least for 'newbies' or others like me who was given a serial/RS232 PIC programmer. 
The other 'issue' is that most new hardware, laptops and desktops, don't have serial ports. So the 'user' is forced to use a USB to RS232 adapter. This 'adapter' does not have the correct RS232 voltages on its pins... So any circuit connected to it does not get the correct voltage [higher than 5 Volts]. For example: Several packet modems would not function with the later models [9 pin] interfaces. These modems were [correctly] designed to connect to a 'real' RS232 interface. Which goes negative with respect to the ground [0V] pin. The interface circuit required the pins to go below -3 Volts for correct switching. This is to improve the noise immunity of the circuit.
With the PIC programmers, it is a case of cheap [sorry cost effective] design. So that the programming voltag…

Some things will never work!

A circuit that I found the other day...

Having shorted out the crystal, I doubt the circuit will oscillate. But you never know for sure. Maybe at VHF?
Another circuit I found recently was a sound card interface for a transceiver. It uses an opto-coupler to isolate the PC's serial port from the radio...
Apart from the fact that in general there should be no need for isolation, the person who put this circuit together, forgot the RS232 specification...

So put a diode across pins 1 and 2 in the opposite polarity. Just to protect the opto-coupler.

Our recent Ham-Comp session, had more people visiting the club. More interested parties and some lessons learned. 
WSPR for the Raspberry Pi
The 'main' wspr site
The GitHub links:-