Running an ESU 73100 Decoder Without Speaker?

[conrad]

Thinking of installing 73100's into several locos but first need to check out power & motor connects and space for speaker.

Can I do a temp install without the speaker connected?  OR Do i need a load resistor?

First attempt will be my Atlas GP40-2.  Looks good for power and motor connections but skimpy height for speaker.

Conrad

[peteski]

While I have not done it myself, the Class-D Audio amps used by ESU should be fine operating without a load.  Plus, if a load was required, I would imagine that there would likely be a bold warning in the manual not to run them without a speaker.

[nightmare0331]

sure.  it won't hurt the decoder if you run it without a speaker.

Enjoy!

Kelley.
www.dufordmodelworks.com

[RBrodzinsky]

Just make sure the speaker wires, if installed, are insulated at the ends and do not come into contact with anything during your testing (better yet, remove them)

[ednadolski]

When the speaker wires are open-circuited, they don't draw any current so there should be no way that could harm (ie, overload) the circuit.  Same for the motor leads.

Ed

[peteski]

Conrad probably recalls some early HiFi home stereo amps which would get damaged if they did not have load connected to the speaker outputs.

[conrad]

Petski hit the nail on the head.  My undergrad ee education was in half vacuum tubes and half discrete transistors.  I sort of remember class A, B & C audio amps and the 10lb output xfmrs.  I think the high voltage B+ ran through the transformer's primary.

Interestingly, a quick search of wiki shows that class D was invented in England ca. mid 50's and, surprise, surprise, put out by Sinclair.  The company that later came out with the "fabulous" $100 Timex Sinclair.

Conrad

[peteski]

Petski hit the nail on the head.  My undergrad ee education was in half vacuum tubes and half discrete transistors.  I sort of remember class A, B & C audio amps and the 10lb output xfmrs.  I think the high voltage B+ ran through the transformer's primary.

Interestingly, a quick search of wiki shows that class D was invented in England ca. mid 50's and, surprise, surprise, put out by Sinclair.  The company that later came out with the "fabulous" $100 Timex Sinclair.

Conrad

Yes, Class-D ("D" also conveniently could stand for "Digital") are very efficient amplifiers, since they use some form of pulse modulation (similar to the way the PWM motor drivers work in DCC decoders).  Since the output transistors are either fully on or off, very little power is wasted as heat.  Unlike analog amps where good portion of the power has to be wasted as heat.  Class-D amps usually do not need a coupling capacitor or transformer, to they can be smaller that their analog counterparts. Class-D amps are also perfect for use in miniaturized applications (like N scale decoders), since they do not heat up much.

Sinclair Radionics brings back some memories.  As a teenager (traveling between USA and Poland) I received a Sinclair microvision portable TV set as a gift from my mom.  It was quite expensive, but she got it for me anyway. It was a tiny battery-powered set that could handle multiple TV standards (like PAL and NTSC).  I still have it, but with new TV transmission standards it is useless.



And the Sinclair ZX81 computer got me started on my career path.  It came out around the time I was in High School.  It cost $150 assembled or $99 as a kit.  I bought the kit, assembled it, and learned both BASIC, and Z80 assembly language on it.  Thanks to that hobby I ended up working in the computer field (where I still work).

[ednadolski]

... the "fabulous" $100 Timex Sinclair.

LOL, I remember that!  With the membrane 'keyboard' and the 16k extended memory module that would develop amnesia as soon as you tried to run the program that you just typed in from scratch...

Ed

[peteski]

LOL, I remember that!  With the membrane 'keyboard' and the 16k extended memory module that would develop amnesia as soon as you tried to run the program that you just typed in from scratch...

Ed

That's the one!   I ended up building my own 64k memory expansion, then made a full-size keyboard, and added a floppy controller with a dual 5.25" floppy drive (IIRC single-sided, single-density). I also added a Sinclair printer which used an unconventional printing method. I even build a light-pen for it, but it wasn't very reliable.  Oh, I also added a 300 baud modem. I used spend hours on  BBS's.   

This is the rebadged ZX81 (after they started using Timex to distribute these little wonders in USA).