Those cheap 12vdc-120vac inverters

[Jim Land]

Curious about those cheap 12vdc-120vac inverters you can buy now.

1. What kind of waveform do they put out? Square wave?

2. Is it possible to damage a piece of electronics using one? Plugging in
a radio, tv, laptop PC, what could the inverter do that would damage the
electronics?

3. If the electronics draws too many amps from the inverter, what will be
the result? Damaged inverter? Damaged electronics?

 

[petrus bitbyter]

Curious about those cheap 12vdc-120vac inverters you can buy now.

1. What kind of waveform do they put out? Square wave?

Usually so called modified sine wave. That's no sine at all but an
alternating pulse with a pause between them.

2. Is it possible to damage a piece of electronics using one? Plugging in
a radio, tv, laptop PC, what could the inverter do that would damage the
electronics?

Some older equipment and motors do not like these pulses and dimmers using
phase control may have big problems. And yes, they can become seriously
damaged. Equipment using SMPS will usually run well as the incoming AC will
be rectified anyway.

3. If the electronics draws too many amps from the inverter, what will be
the result? Damaged inverter? Damaged electronics?

Blown fuse.

petrus bitbyter

 

[James Sweet]

Curious about those cheap 12vdc-120vac inverters you can buy now.

1. What kind of waveform do they put out? Square wave?

2. Is it possible to damage a piece of electronics using one? Plugging in
a radio, tv, laptop PC, what could the inverter do that would damage the
electronics?

3. If the electronics draws too many amps from the inverter, what will be
the result? Damaged inverter? Damaged electronics?

They put out an ugly squarish wave.

I run my laptop from one, it works just fine.

Usually the inverter will just shut down.

 

[Michael Kennedy]

You can make a cheap sine wave inverter out of an old APC Smart-ups.. I did
and it works great. The key is it has to be a Smart-ups.. Back-ups models
ouput a square wave.

- Mike

 

[Bill Jeffrey]

Usually so called modified sine wave. That's no sine at all but an
alternating pulse with a pause between them.

--------------------
I'm under the impression that most modified-sine-wave inverters put out
a stairstep approximation to a sine wave. Not necessariy very many
steps, but certainly better than pulse-pause-pulse.

Bill

 

[William R. Walsh]

Hi!

1. What kind of waveform do they put out? Square wave?

Dunno for sure...I've seen references to modified sine wave units.

2. Is it possible to damage a piece of electronics using one? Plugging in
a radio, tv, laptop PC, what could the inverter do that would damage the
electronics?

Yes, it could be. I have a StatPower Portawattz (or something similar)
inverter that I bought reconditioned several years ago. The manual that came
with it had several things to say about this topic. I don't recall what all
was mentioned, but cordless drill chargers with notices printed about high
voltage present near the charging contacts were on it.

The only thing I've ever burned up or damaged on it was an X-10 remote
control module. (Don't ask. ) I've run computers, TV sets, box fans,
printers, clocks (with varying results in terms of clock accuracy), a stereo
receiver, laptop power bricks, and even a few lamps. They all worked
acceptably well.

3. If the electronics draws too many amps from the inverter, what will be
the result? Damaged inverter? Damaged electronics?

The inverter I have has been pretty good about this. It simply shuts down
with a loud beep and a red LED if it is overloaded or the battery voltage
falls below 10VDC. Any behavior is possible, but bad things generally
shouldn't happen. The worst case scenario that I'd consider acceptable would
be failure of a fuse in the inverter. Anything else failing inside it would
seem to indicate poor design.

William