[time-nuts] the end of light bulbs as we know it was Re: Safe power-up. was (Solartron 7075 ...)

John Howell j at howell61.f9.co.uk
Wed Oct 12 05:10:03 EDT 2011


Your mention of bridges Chris reminds me that the British Post Office developed quartz oscillators in the early 1940s that used filament lamps for amplitude stabilisation in a bridge circuit. Stabilities of ±1 part in 10 to the 8th were achieved.

John H.

On 12 Oct 2011, at 06:00, Chris Albertson wrote:

> Another connection from Time Nuts to incandescent light bulbs is the early
> HP Wien bridge oscillators.  They used the light bulb for amplitude
> stabilization. This light bulb stabilized oscillator is what put the HP
> company on the map.
> 
> There was a time when these oscillators where the best available.  I have
> one of these and it still produces a good distortion free signal for testing
> and measurement of audio gear.
> 
> On Tue, Oct 11, 2011 at 6:06 PM, John Howell <j at howell61.f9.co.uk> wrote:
> 
>> Sorry Tom, (again!),
>> 
>> Just as significant is the radiation from compact fluorescent lamps, many
>> radiate strongly in the 50-60KHz region from their SMPSs. This has been the
>> reason for failure of several clocks I am aware of that are tuned to
>> radiocode transmissions on 60KHz.
>> 
>> John H.
>> 
>> On 12 Oct 2011, at 01:28, Gerald Molenkamp wrote:
>> 
>>> Hi All,
>>> 
>>> Sorry Tom, worth a mention.
>>> 
>>> I replaced all of my down lights after my Kids wanted us to contribute
>>> to lowering our carbon footprint. On the positive side, moving to LEDs
>>> will provide savings around $107/year in electricity charges.
>>> 
>>> 
>>> 
>>> Now to the negative part , noise floor from around 21MHz to well over
>>> 500MHz raised to a signal strength 5 to 6 across mid to upper HF / lower
>>> VHF to upper UHF with them switched on, otherwise my noise floor is
>>> Zero.
>>> 
>>> Lower VHF  to UHF SSB/FM low level signal work is now not possible when
>>> LEDs are on, mostly at night when we enjoy the hobby.
>>> 
>>> The net effect of dirty LED lighting has long term issues with sensitive
>>> receivers.
>>> 
>>> Regards
>>> 
>>> Gerald
>>> 
>>> VK3GJM
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> There is one angle that was not covered, but which is relevant (at least
>>> to those of us using any LF or HF time receivers).
>>> 
>>> Over the weekend I bought my first LED bulb.  It was on sale and I
>>> wanted to see how it worked.  On the package it gave a warning that it
>>> could interfere with HF communications in the 0.45 - 30 MHz range and to
>>> not install it near any maritime emergency communications equipment.
>>> 
>>> Peter
>>> 
>>> 
>>> On 10/11/2011 6:56 PM, Tom Van Baak wrote:
>>>> This thread is wonderful, nostalgic, technical, futuristic, and
>>>> appropriate for someone's list. But not time-nuts. Please stop it now.
>>> 
>>>> Don't reply.
>>>> 
>>>> /tvb
>>> 
>>> 
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> 
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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