Thursday, 9 January 2014

Setting up and Testing the Raspberry Pi Wobbulator - Part 3

With my Raspberry Pi Wobbulator powered up and ready for action the first task I decided to give it was to examine the frequency response characteristics of an RF crystal. If this sounds familiar, then it is because it is. I performed the same test using the revised Raspberry Pi prototype - see this previous post for details. I'm repeating the same test using the "production version" of the RPi Wobbulator to provide a direct comparison.

The first test was performed using Channel 1 - the linear input. The frequency sweep was performed with nothing connected to the input of Channel 1 (bottom blue trace), with the output from the DDS module fed directly into the input of Channel 1 (top blue line) and finally with the RF crystal connected between the output from the DDS and the input of Channel 1 (red plot).


The results obtained were virtually identical to those obtained when using the revised prototype.

The same test was then performed using Channel 2 - the logarithmic input.


Once again the results were very similar to those obtained using the revised prototype.

So, the "production version" of the Raspberry Pi Wobbulator seems to be performing very well! For details of further testing and details of other users experiences building and using the RPi Wobbulator please visit the Yahoo group.

If you would like to purchase a Raspberry Pi Wobbulator PCB or PCB and full component kit then please visit www.cutpricecables.co.uk/irpiwobbulator.html . The PCB is priced at £12.00, and the PCB plus kit of components is priced at £40. This includes all sales taxes and free worldwide delivery. You can purchase online and pay by credit or debit card, or PayPal.

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