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I'm looking to power one of these bits of film with a 12v DC battery.

PDLC Electrochromic Film / Switchable Glass

https://www.ebay.com.au/itm/200-x-300mm-PDLC-Electrochromic-Film-Smart-Film-Starter-Kit-Switchable-Glass/322846672969?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

I believe they operate at 60vac.

I guess it'll involve a dc-ac inverter that will output something like 240vac or 110vac. then gettting an adjustable voltage regulator to step down the voltage to 60v.

I haven't done a lot of work with AC so I don't know the terminology for the components.

What's the easiest and cheapest way to get 60vac from 12vdc? is there such a thing as an all-in-one DC to adjustable AC inverter? or will I need at least two components.

bonus round:

  1. what would happen if I just put dc in to this film?

  2. can you use PWM for dimming with AC circuits?

thanks heaps

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Regarding the operating voltage, it looks like these "switchable glass" devices work similarly to LCD's and will require an AC drive voltage to prevent damage over time.

Smart glass handbook (Courtesy of google)

http://www.smartglassinternational.com/downloads/LC_SmartGlass_Handbook.pdf

As to what the frequency of this voltage has to be I have no idea, assuming a transformer in your ebay link, around 50/60 Hz.

An EL wire inverter (ebay link below) claims to put out >100V AC so may be too much voltage to use directly. Also the output frequency is not stated, but el wire apparently works between 400 & 2000 Hz so is probably somewhere in that range. This may or may not be suitable.

To make it adjustable you might be able to vary the input voltage with something like a buck/boost converter module (assuming the inverter has no regulation)

This is much easier than regulating AC

Note that varying input voltage may also vary the output frequency of the inverter!

Buck/boost converter module:

https://www.ebay.com/itm/Boost-Buck-DC-adjustable-step-up-down-Converter-XL6009-Module-Voltage-NEW/191673952440?epid=911606552&hash=item2ca0a868b8:g:0CAAAOSwLVZVs4ch

Inverter module:

https://www.ebay.com/itm/Mini-DC12V-1-5M-EL-Wire-Cable-Neon-Glow-Strip-Light-Power-Driver-Inverter-New/182701362456?hash=item2a89d98d18:g:rLMAAOSwxDNZhBiM

Basically:

1)You have to use AC, DC will damage it and probably wont even work

2)Not sure about exact drive voltage/Frequency...

3)There are better solutions than the one above as its a bit of a hack

4) Ideally you would want to build a proper driver

This ebay listing shows some of that PLDC film with what looks like a battery powered El wire driver so maybe higher frequencies will work? As to how good for the film this is im not sure...

https://www.ebay.com/itm/15X15cm-White-Smart-PDLC-Film-Switchable-Privacy-Glass-Electrochromic-Sample/282768238917?epid=11011203602&hash=item41d64ce945:g:eqkAAOSwWclZeuJW

Also, the power required will vary depending on the amount of film you are going to be driving.

As for dimming, I don't think this film is fast enough in terms of switching times. You would likely end up with nasty strobing effects.

Dimming in AC tends to require chopping up the waveform with something like a triac.

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  • \$\begingroup\$ so MAYBE I can buck the 12vdc supply down a bit and feed it in to an EL inverter which SHOULD drop the 110vac output down. and this might also change the frequency. guessing it'll drop the frequency if anything? \$\endgroup\$ – totalconfusion May 10 '18 at 17:07
  • \$\begingroup\$ yes maybe, frequency may go either way depending on the oscillator inside the inverter. You would have to measure \$\endgroup\$ – del-eng May 10 '18 at 19:47
  • \$\begingroup\$ Just found this spec sheet ( wxalbum-10001658.image.myqcloud.com/wxalbum/48927/… ) It looks like the film will take 30-400hz but works best at 50-100hz. \$\endgroup\$ – totalconfusion May 11 '18 at 3:34
  • \$\begingroup\$ To get the 50Hz a standard power inverter would work but at to much voltage. a 12V to 110V AC 60Hz inverter would also be overkill. You could use a resistive or capacitive divider to drop the OP volts however. Using a dropper wold waste power and be a bit dangerous as you start dealing with mains voltage/current. \$\endgroup\$ – del-eng May 11 '18 at 11:42
  • \$\begingroup\$ Some of those sampler pieces come with those battery packs. Problem is, the switch is a temporary push-once-on, push-once-off toggle type switch. Is there any easy way to figure out how to wire it as a logic switch? e.g. to be controlled by a gpio? \$\endgroup\$ – Scott Wood Apr 16 at 15:12

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