EMRFD Message Archive 9906

Message Date From Subject
9906 2014-04-10 08:11:12 Alberto I2PHD Wide range oscillator
Greetings all,

  I am in search of the schematic of a simple LC oscillator, using easy to find parts,
whose C component could range from, say, 1000 pF to 10 uF with the oscillator
working without problems on the entire range.

The L component is not critical, a value of 60 uH would make the oscillation frequency
from about 650 kHz (with 1000 pF) to about 6500 Hz (with 10 uF).

You have already guessed the purpose... I want to replicate the AADE LC meter, but with
an extended range and using a Stellaris board complete of a touch screen TFT display
as a controller. If I obtain satisfactory results, all will be published open source.


Thanks for any suggestions

--
73 Alberto I2PHD
Credo Quia Absurdum Est Credo Ut Intelligam


9907 2014-04-10 08:23:04 Roelof Bakker Re: Wide range oscillator
Hello Alberto,

Can you give the frequencies you need for the LC meter?

73,
Roelof, PAoRDT
9908 2014-04-10 09:22:11 Alberto I2PHD Re: Wide range oscillator
9909 2014-04-10 10:05:29 Roelof Bakker Re: Wide range oscillator
Hello Alberto,

10 uF is a bit unwieldy for a LC oscillator.
Can't you use a NE555 type oscillator?

73,
Roelof, PAoRDT
9910 2014-04-10 10:13:08 Alberto I2PHD Re: Wide range oscillator
9911 2014-04-10 10:29:56 Leon Heller Re: Wide range oscillator
9912 2014-04-10 10:44:29 Alberto I2PHD Re: Wide range oscillator
9913 2014-04-10 10:58:43 Leon Heller Re: Wide range oscillator
9914 2014-04-10 13:14:30 Sandeep Lohia Re: Wide range oscillator
Hi Alberto,
what U thinks ( TFT display ), components might not be available
everywhere easily.
Here I used internal oscillator of more economic PIC...

http://www.qsl.net/vu2upx/Projects/2tosc.htm as I know that site is
no longer maintained by Charu...

btw, I did forward your mail to him, good in codes too...



--
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9915 2014-04-10 13:55:00 Alberto I2PHD Re: Wide range oscillator
9916 2014-04-10 14:08:33 Alberto I2PHD Re: Wide range oscillator
9917 2014-04-11 03:15:23 g3wie Re: Wide range oscillator
Hi Alberto,

Here's a "cascode" oscillator circuit which oscillates from kHz to a few hundred MHz using a negative-resistance simulation. This was published in the GQRP magazine SPRAT by LZ1OV, and republished a couple of years ago with a PCB layout. Stefan made some PCBs and I kitted them up and sent them to GQRP to sell in their shop, though it would be better to build it ugly-style for the best VHF performance. The output waveform isn't too nice; adjustment of the bias values might improve it. Apart from the tuned circuit, there are no frequency-sensitive components.

I couldn't see how to attach the schematic to this post so perhaps this link will work (it's in the G3WIE folder in files)
https://xa.yimg.com/df/emrfd/cascode_osc.jpg?token=7fbNhJTrF-xS7dx2cym2qxVxk8jz9tO6YQMGtJSWp6RCOQ5pGM57ZCKGvuPA79EI3r2tp_q8omA5EE3NMO-g_PRPUljBZ039vvtVPAmrJo9fmkxd&type=download

73

Chris
G3WIE

---In emrfd@yahoogroups.com, wrote :

Greetings all,

  I am in search of the schematic of a simple LC oscillator, using easy to find parts, whose C component could range from, say, 1000 pF to 10 uF with the oscillator working without problems on the entire range.