LED displays (TIL305, TIL308, etc.)

[Chuck Guzis]

On 3 Oct 2008 at 21:29, Tony Duell wrote:

> I am suprised that motors objected to too low a voltage. Wasn't there a 
> frequency difference too -- I thought that some of Japan was 50Hz. That 
> might have been more of a problem

Induction motors run on too-low voltage tend to draw too much 
current, leading to overheating, particularly in those applications 
where a more-or-less constant load that runs the motor near its 
nameplate rating is encountered.  You can sometimes find under-
voltage protection devices on industrial equipment motors.  Many 
small motors are impedance-protected, so operating, say, an equipment 
cooling fan motor on low voltage is probably safe.

On the other hand, I've run 220v 25Hz induction motors on 120v 60Hz 
just fine--or at least they didn't burn up.  

> I'd seen 45V batteries listed, but I assumed (incorrectly, I guess) that 
> they were normally used in pairs to give 90V. I've never seen a radio 
> that used them, I do have one device, totally off-topic, that should use one.

The 45v batteries were widely used in photoflash units, as well as 
some early portable radios.  67.5 and 90v batters were also used here-
-and then for photographic strobe applications, 225, 450 and 510v dry 
batteries for very fast recovery times.  510v was the highest-voltage 
widely-available primary battery that I'm aware of. 

Cheers,
Chuck