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?

Now I have a home burglar alarm that might be in the alarm status. I
can't tell because I disconnected part of it, until I can find out how
to disarm it.

I have two horns and a siren driving amplifier board, so that they're
louder than the mere alarm control panel can provide. I have a glass
fuse in the line to each speaker.

So if I take the fuse out 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?

What if I disconnect the siren driver from the control panel? 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?


Those are the questions. The rest here is just a narrative, soon to be a
major motion picture.

20 hours is how long I need to look into it, sleep, and then contact my
friend who runs an alarm business. But I'd really like to do as much as
possible on my own. He's constantly doing favors for me and a couple
days ago he wanted to send over his technician to finish the
installation for me. I can offer to pay; i can insist on paying, but I
know he won't let me, and, trust my judgment, he probably wants the
kavod of helping me more than he wants the money. Plus my own ego is
involved in wanting to do it myself...., so I really shouldn't be asking
you any questions either. But it's different. None of you are coming to
my house to do it.

The reason it's running is that I tried the original default master
code, several times, and it didn't work. It wouldn't arm the system,
but I wanted to hear if the siren worked (this system has never been
tested before) and soon I got the bright idea to arm it another way.
there is an Away button which when pushed for 2 seconds arms it without
the code. Well the siren works, as well as it did when I had my
previous system installed (designed and installed by me, but it burned
out after 15 years. Lightning?) but I didn't look far enough ahead to
realize still didn't have a code that worked and I have no way to turn
it off.

Well, I unplugged it, and the battery hasn't been charged in 9 years, so
that turned it off, but I need to work on it and the moment I plugged it
in again, it armed itself.

You are either going to have to call the alarm manufacturer, or find the original owners manual.

Many (not all) alarms, however, will default to 1234# if there is a power failure long enough to drain the battery, and whatever process holds the memory. This is a slim-to-none chance, but probably worth taking.

Our ADT system defaulted this way after about 2 years of downtime. We switched systems as ADT wanted an obscene monthly fee and a very long contract.

Peter Wieck
Melrose Park, PA

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?

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.

"That was only ever a problem with tube (valve) designs. "

That is only partly true. Solid state amps that have output transformers or chokes are also vulnerable. In fact Delco car radios had a warning sticker on them that read "DO NOT OPERATE WITHOUT LOAD". Those were a class A open ended stage simply running into an inductor, but it did produce more power than the SESAPP at a given voltage. It was actually capable of almost nine wattts nto eight ohms but they didn''t bias them hard enough to hit that level without distortion.

Any amp that uses an outpur transformer or choke can be damaged if operated without a load. The old tube stuff, what was actually the problem there was the tube sockets themselves because of the unbridled inductive kick when they got clipped with no load.

I've been in the argument about tubes and don't want to dwell on it, but one thing to remember is that a triode is still a diod, a tetrode is still a diode. When you get to a pentode maybe not so much because of the suppressor grid, but most of the other ones simply do not conduct in reverse. Generally the output devices and transformers could handle the voltage, what happened alot was that the tube sockets arced over.

The failure mode is different in a solid state unit. The inductive kick causes forward current to flow in the collector to base junction and the transistor really does not like that.

From what I've read a bit more recently, because there are still tube amps around, especially for guitars and these high MFs might forget to plug in the speaker, (oh, I got tons of stories about musicians, I mean, nice guys usually but electroncs is like speaking Martian to some of them) now some designs include a diode to ground from the plates of the output tubes. This limits, actually damps, the inductive kick in case a speaker is not connected. However one tech around here reported that he had some problems adding such diodes to an existing design, and I never got the full details on that. It's just not something I have explored and queried about.

Anyway, getting to the OP here, the main thing is simply to look at the unit and see if it uses an output transformer or choke. If not, most solid state equipment can run full blast for decades into no load. However, not knowing the impedance of the guy's siren or whatever, there might be a step up transformer to drive it. Actually that would tend to be less susceptable to such damage than an output circuit that steps down.

When they got to OTL (output transformerless) SESAPP (series arranged, single ended push pull) circuitry the danger was pretty much gone unless the design itself was defective. Or people. I remember working on a Harmon Kardon Citation 12 and people said you could use 2N3055 for outputs. NOPE. The voltage Vcb is not high enough. Now in THAT case because the load is not pulling down the power supploy rails there might be a prblem, especially iif you have transistors that are margnal. Those ratings on the spec sheets are MINIMUM, or WORST CASE. Personally I just use 2N3773s in something like that, which have a nice smooth gain curve as well.

Bottom line, most stuff doesn't care if there is a load. Exceptions are far and few between unless you deal with old stuff or tube stuff. This is supposedly an alarm system, and those barely existed in 1963 when this could be an issue.

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) ????