ELEKTOR FORUMS

Hello all - I have built the 'EM84 USB Magic Eye' CPU load monitor circuit as published in January's issue.

The tube indicator bars glow dimmly, accompanied by a slight whistle from the transformer. The HT is 216V, but the heater voltage is very low indeed.

I read that the heater supply voltage / current is PWM controlled by the PC software, and this is where my problems start.......

When the monitor is plugged into a USB port, 'Device not recognised' appears - it does not even ask for a driver. I've downloaded the AVR309.zip file from the ATMEL website and have the nessecary drivers, but don't know where to begin installing the AVR software ??


Any help would be greatly appreceiated

Many thanks, Richard

Many thanks for the reply - all sorted now

Stupid mistake - misprogramed the fuses on the ATTINY.

Now needs a bit of tweaking, as I wound the transformer on a 'non-spec' former - HT now nearly 300V ! - so it will all have come to bits again.

Picture attached shows running at 20% - a bit out of sorts.

DOS Command line : cpushow 20


Richard

Just built this with a moving coil meter, very useful. At least now I can see the computer is 'doing something' when it seems to be 'doing nothing'!

I wonder though, is there a way to run the PC application without having a window sitting on the task bar? I tend to have many things running at the same time, so the less items on the task bar the better. Any ideas??

Hi Godfrey,

I recall having the same problem actually. I tried various combinations until it worked! The attachment shows the settings in my programmer's software - hopefully thats easy to translate to your programmer's.

Is this what you're looking for?

http://www.elektor.com/magazines/2010/january/usb-magic-eye.1191254.lynkx?tab=4

Thats all there is I'm afraid. If it doesn't work on Win7 or Vista I think thats the end of your project. Try googling AVR309 and see what you can find.