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HV850 EL driver hacks

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Conundrum

Sun Oct 09 2011, 09:30PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Hi all.

Have just received these, and hooked one up to test.

As expected they can be hand soldered even though smaller than SOIC.

I used the "ghetto" hack of a broken 4000 series IC chopped with wire cutters, sanded down
then fine wire attached to each pin as an interconnect.
Used 40 gauge solder to connect, cleaned up with solder wick and all works fine.

Connected one up with the basic 1Mohm R_EL and it works fine, drawing around 4.4mA and putting out
50V peak (i.e. 100V p-p) into the EL wire.

These can also be used to drive small piezo speakers for small ornithopters, although not really designed for this as long as the capacitance is less than 8nF they work fine.

The hack I have in mind is to drive two with offset clocks from a PIC uC and then connect each opposing output to the
input pins on a piezo transformer.
Idea here is that at acoustic resonance I should get around 1600V p-p with only a 10mA 4.2V input.

Sound feasible?

These also make great micro EL drivers, as long as you don't mind only being able to drive 2" of wire at a time.
The best wire for these is probably the "angel hair" type which I am still waiting on.

UPDATE:- Thanks elwirecraft

As expected this is the slightly tinted one BUT it does noticeably change colour when the drive frequency is varied.

I also found that the EN input on these chips can be used as a voltage sensor if you add a divider, so an EL bargraph is simple to do.

Also BE CAREFUL and read the datasheet. If you forget to put a 0.1uF capacitor across the power lines then the chip
will work at 3% of its rated current and behave unpredictably.

Another hack I came up with is to put a 4.7nF capacitor in series with the EL drive, then connect the output to an LED string.
The plan here is that current draw is fairly low due to series impedance but the brightness is pretty good.

You can drive up to 2*15 white LEDs in inverse parallel from a single HV850, so ideal for picture frame hacks etc where you don't need high brightness.

-A

Xray

Sat Oct 15 2011, 03:34AM

Registered Member #3429 Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288

Conundrum wrote ...

Hi all.

Have just received these, and hooked one up to test.

As expected they can be hand soldered even though smaller than SOIC.

I used the "ghetto" hack of a broken 4000 series IC chopped with wire cutters, sanded down
then fine wire attached to each pin as an interconnect.
Used 40 gauge solder to connect, cleaned up with solder wick and all works fine.

Why would anyone "ghetto hack" a broken 4000 series IC? They are so cheap, they are practically FREE! So, why waste your time chopping, sanding, and soldering fine wires, when you can buy brand new IC's for pennies?

wrote ...

Connected one up with the basic 1Mohm R_EL and it works fine, drawing around 4.4mA and putting out
50V peak (i.e. 100V p-p) into the EL wire.

What is a "R_EL"?

wrote ...

These can also be used to drive small piezo speakers for small ornithopters, although not really designed for this as long as the capacitance is less than 8nF they work fine.

The hack I have in mind is to drive two with offset clocks from a PIC uC and then connect each opposing output to the
input pins on a piezo transformer.
Idea here is that at acoustic resonance I should get around 1600V p-p with only a 10mA 4.2V input.
Sound feasible?

Sure, it sounds doable, but it's a complex way to do something that can be done with a much simpler circuit. You can get 1600V @ 10mA with a simple oscillator driving a step-up transformer or flyback.

wrote ...

These also make great micro EL drivers, as long as you don't mind only being able to drive 2" of wire at a time.
The best wire for these is probably the "angel hair" type which I am still waiting on.

I'm not familiar with "driving wire", so for those of us who don't know what you are talking about, could you please explain?

Conundrum

Sat Oct 15 2011, 11:15PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Hi..

R_EL is the resistor which determines the electroluminescent sheet or wire drive frequency.

Well the reason I want to use this setup is that the circuit needs to be very very lightweight so it can be magnetically levitated.

Using any sort of wound component would be too heavy.

"Ghetto hack" i.e. use a 4000 series IC as a host to hold a ridiculously small SOIC IC to use on a breadboard.

It came back to bite me though, there was a leak on three of the pins (facepalm)

So my next project is a few SOIC to DIL adaptors with space for two HV8xx IC's, a PIC 10F20x and their support components.

"Driving wire" refers to driving EL wire.

-A

Xray

Sun Oct 16 2011, 02:05AM

Registered Member #3429 Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288

Conundrum wrote ...

"Driving wire" refers to driving EL wire.

-A

I never heard of "EL wire" before, so I had to Google it. Now I know what EL wire is.

Conundrum

Tue Nov 01 2011, 07:50AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Bit late but hey....

Idea, single chip EL flasher.

The plan here is that an MPSA42 can be used as double duty.
Use a single inductor on the collector as the transistor can tolerate
>100V peak.
Then drive the base from the HV850 clock output via a resistor,
this works because the HV850 has an internal divide by 128 so
only one part is needed instead of four.

Then use the "bootstrap" technique to generate the 4.5V Vcc voltage.
i.e. use a series resistor and diode from TR1 collector to Vcc,
this also means that a single 1.5V cell can be used for power.

Need a push button to start/stop, the idea here is that the initial
surge current starts the oscillator but an extended press shuts it down.

Because the TR1 collector is oscillating at >100V if this output is rectified
it can be used to double the V_EL as the output is an H bridge.

If the EL is driven at a low frequency of say 2 Hz it should then flash the EL
wires alternately which doubles the effective drive power.

This is absolutely brilliant if it works

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