On Sun, 26 Feb 2017 06:27:32 -0500, Pat wrote:

On Sun, 26 Feb 2017 03:39:55 -0500, micky
wrote:

Thanks for the reply pf, but I'm still interested in the questions.


Years ago, I was told not to play my stereo with no speakers, for fear
of somethun' or other. Of course that was 1968, a good year for audio.

Is this still an issue with current electronics, like audio amplifiers
and burglar alarm amplifiers?


So if I take the fuse out of the circuit to the sirens, but the siren
driver is still functioning, do I risk burning it out? Even if it's
like this for say, 20 hours? Or can it go like this with no harm to
itself?

(These 3 questions are still important regardless of whether I
disconnect the siren driver from the control board.)

But.. what if I disconnect the siren driver from the control panel
(which I did)? They're separate boards. Do I risk burning out the
output of the alarm control panel, if say it is run. again, 20 hours?
Or can it go like this with no harm to itself?

That was only ever a problem with tube (valve) designs. No load could
cause the output voltage to rise enough to damage some components. I
am not aware of any modern equipment with similar restrictions. When
transistor outputs arrives to replace tubes, that was one of the big
advantages. You didn't want to short the outputs, but having them
open was no problem at all.

Yea, big tube amps should not be run at high volume for any length of
time with no load (speakers or resistors) connected. But this was not
really true for small amps. like and old tube table radio, portable
record player, etc. I never had any problems running that small stuff
without a speaker. For power amps, guitar amps, PA systems or high
powerred stereos, I had a pair of 8 Ohm 100W wirewound resistors to
place across the spkr terminals.

I am not sure if I agree about the no need for speakers on the EARLY
solid state devices. Sure you could run a pocket transistor radio with
no load, and it would be fine, but I was told to NEVER run those early
power amps without a load, and told that they would fry the output
transistors a lot faster than a tube amp would be harmed.

Just because I was told this, does not make it true. That was in the
early 1970s, and most of my information was from magazines (like Popular
Electronics), or word of mouth from employees or other customers I ran
across at electronics parts stores.

I have heard that modern solid state devices are safe to run without a
load, but I dont think I'd try it for any length of time on anything
that outputs more than 5W. Particulary if there is an input source.

To be safe, go on ebay and buy a suitable resistor. I just looked and
you can buy a 8 ohm 100W wirewound resistor for as little as $3. For $3,
why take a chance, esp if you plan to run it for 20 hours. And that
resistor can be used in the future for all sorts of repairs on almost
all power amps, except those rated over 100W. (Which you wont likely
encounter).

* Ebay has an 8 ohm 1000W resistor too, for $60. Thats one huge
resistor.

* If you cant get an 8 ohmer, a 10 ohm will work too. Just make sure the
wattage can handle what you are working with.

(I have no clue what the wattage would be on an alarm system) ????