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Dick Moore photo 150 Tronola is pleased and honored to republish here, in its entirety, the sterling website Dick Moore created over a decade in his retirement. We are grateful to his lifelong companion and wife, the Reverend Robin Moore, for her kind support in this endeavor. We are also indebted to Tronola author, Arthur Grannell for his generous efforts to facilitate this publication. Finally, we would like to thank Larry Burk, who first introduced us to Dick’s work, back in 2012.
Electronics enthusiasts lost a great friend and contributor in November, 2015. Dick Moore had been actively helping and creating in the audio e­lec­tron­ics field for over fifty years. He once worked with Paul Klipsch and among other things, worked on positioning the drivers in the famous Cornwall speakers. I knew him through his remarkable series of “greenings” of the Heathkit IG-18 audio generator, which happily intersected with our own efforts, as related in our Tronola article on the subject. Our focus here belies the rich life Dick led and you can find out more here.
— S. Lafferty, December, 2016


  Home -- article index
  60kHz Shielded Loop Antenna             updated 10-16-2010
  GPS-Disciplined 10MHz Oscillator 1             updated 9-6-2008
  GPS-Disciplined 10MHz Oscillator 2             updated 4-14-2014
  Heating/Cooling Load Calculations             updated 6-16-2013
  Hot-tub PID Heater Control             updated 1-11-2012
  Hot-tub PID Heater Control Rebuild             new page 4-15-2012
  Pure beauty: The Sine Wave             created 11-11-2014
  About RC Oscillators             updated 10-26-2011
  Lamps for Stabilizing Oscillators             updated 10-9-2011
  Heath IG-18 Oscillator #1 -- re-greened original             updated 5-23-2011
  Heath IG-18 Oscillator #2 -- Cordell's SV design             rewritten 6-29-2012
  Heath IG-18 Oscillator #3 -- HP's 339A design             updated 6-11-2012
  Heath IG-18 Oscillator #4 -- HP 339A variant             created 6-14-2012, updated 8-11-2012
  About Total Harmonic Distortion Analyzers             updated 4-28-2015
  Active Twin‑T Notch Filter             updated 12-16-2014
  Greening the HP 334A Distortion  Analyzer             complete rewrite 6-25-2012
  Mod of Heath IP-2718 Triple Output Power Supply             updated 6-18-2011
  Repair & Mod of GR 1562‑ ;A Sound Level Calibrator             updated 7-26-2012
  Received Wisdom
      Welcome. Please post below if you have any questions about stuff on the site.

Spring rhody

Spring rhododendron in Grapeview, Washington, USA

© 2005-2015 Dick Moore   


Reader Comments

Posted by Steve L. November 11, 2021 - 10:36 am
Hi Gary, Thank you for your comments about Dick Moore's article, "Lamps for stabilizing oscillators", linked above. Incidentally, in the section of Dick's article, "The trouble with lamps," he's referring to the dynamic stability issue of the automatic level control (ALC), as opposed to long-term frequency stability. The Heathkit IG-18 is a lamp-stabilized oscillator. In my ancient, personal history of IG-18 mods to reduce distortion, I found that the lower I could get the distortion, the longer it took for the amplitude to stop bouncing up and down. In the end, I had to choose between lower distortion or shorter settling time. As Dick suggested, how this tradeoff turns out depends in part on the thermal mass of the filament and related factors.

When I discovered the wonderfully smooth and quick settling of the HP-339A oscillator circuit, combined with its extremely low distortion, I was ecstatic. Hence came the IG-18SL project and the article which resulted. I later heard of Dick Moore's writings about improvements to the IG-18 (linked above) and his very helpful work on the IG-18SL approach. By the way, a supplement to the IG-18SL article is in progress which will introduce a new, professional, PCB for it, along with some much needed improvements. Stay tuned...

But I have to admit, in terms of "bang for the buck," it's hard to beat the light bulb stabilized oscillator, invented by Bill Hewlett circa 1938.

For the benefit of other readers, Gary refers to the Linear Technology datasheet for the LT1037:
--- On the first page is the delightfully simple circuit for a low-distortion, 1kHz oscillator.

Posted by Gary N5TXH November 10, 2021 - 11:54 pm
Hi 'All --- Enjoyed reading about the role of #327 lamp on your article on Wein Oscillator stabilization.
These lamps are available from Mouser in Texas @ $1.80 each... not very expensive at all. My working prototype is based on the Linear Technology pdf for the LT1037, and results in a very stable frequency output of ~ 999.7 hz. The variance is in the 200 milli-hertz range over the past 48 hours with temperatures of 25C +/- 2C... so it's a simple circuit that really performs! Suggest that you carefully match 1% resistors and capacitors and use a multi-turn trim pot instead of the 430 ohm resistor for the best results.

Posted by Steve Lafferty August 06, 2020 - 06:49 pm
Hi Chris, I take it you came here because of Dick Moore's article, "About Total Harmonic Distortion Analyzers," linked above, where he discusses the Sound Technology ST-1700 and light dependent resistors (LDRs). While I don't know of a source for the ones used in the ST-1700, I have built an LDR in the past by combining a cadmium sulfide photocell and an LED, covered with heatshrink. The photocells are readily available, such as this one: If you try that, please come back and let us know how it works in the ST-1700. I will be happy to help if you any other questions. Best wishes, Steve

Posted by Chris Cecil August 06, 2020 - 05:31 pm you have any ideas on a source for replacement LDR's for ST 1700's
Chris Cecil

Posted by Steve L. March 19, 2020 - 04:22 pm
Hi Mark,
Thank you for your kind post. I'm sure Dick would be very pleased to hear it.

Posted by Mark - AA7FY March 19, 2020 - 04:00 pm
Your IP-2718 mod was brilliant. My power supply is sooooo much better.

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