Re: Buzzer tuning question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <teslalist-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:

 > Hi Ed, Coilers,
 >
 > Thanks for the reply.  I may just have to break down and buy a cheap
 > 'scope, but I will give the R.F. voltmeter a try once it warms up so
 > I can be out in my unheated shop again.  I have a textbook a friend
 > gave me published in 1915 titled "Handbook of Technical Instruction
 > for Wireless Telegraphists" which contains a chapter on the testing
 > of spark transmitter circuits with a buzzer.  As you mentioned, it
 > says to connect the buzzer points across the spark gap.
 >
 > 73, Weazle, VE3EAR/VE3WZL

	The problem with the VM may be that it just doesn't have enough
sensitivity - you'll have to try.  That book is just another reminder
that those guys knew what they were doing in "the good old days of
spark".  I might mention that the buzzers used were generally
high-pitched ones (something like 400 cycle tone) so they gave a very
distinctive tone.

	On that same subject and something that might be of interest to all.
I've played around using a buzzer-excited primary circuit coupled to a
variable-tuned secondary.  By looking at the waveforms across the latter
you can observe the effects of change in coupling, detuning, etc.  Just
a couple of coils on the bench which will tune to the same frequency,
secondary need not be high impedance.  You will find that, with the
correct tuning and coupling, the secondary pulse envelope resulting from
each make of the buzzer contacts will become a nice smooth rise and
decay, just the sort of results desired to minimize interference between
"wireless stations".  No quenching, of course, so you can't simulate a
tightly-coupled TC, but still something worth trying.

Ed