MiniPOV as a generic sequencer?

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halley
 
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MiniPOV as a generic sequencer?

Post by halley »

Has anyone played with driving anything other than plain LEDs with the MiniPOV?

I am toying with the idea of making a small water fountain that had a pattern of eight jets turning on and off. Slow down the clock (since this application is not really at POV speeds) and drive valves (probably 12V solenoids) from the LED outputs.

I'd need to figure out a basic circuit to give a high-current 12V to the valves but controlled by the low-current 3V outputs. Relays are not my favorite solution, due to noise and reliability in the long run.

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Re: MiniPOV as a generic sequencer?

Post by adafruit »

you'll need a transistor to drive the solenoids but it should work just fine. im moving the topic to a more suitable forum

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opossum
 
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Re: MiniPOV as a generic sequencer?

Post by opossum »

Image

Transistors can be TIP120,121,122,140,141,142 etc...
Power supply must be at least 4.5V (3 x AA, USB, etc...)
D1-D3 have been changed to 5.1V - this is necessary because the supply voltage is higher.
Use red LEDs (lowest Vf).
Resistors R1-R8 are optional - no need to include them if this is built from scratch.

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halley
 
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Re: MiniPOV as a generic sequencer?

Post by halley »

Thank you, oPossum.

The circles are my peripherals (solenoid water valves), and you're using D1-D8 to ensure against backflow, and you suggest the use of LEDs here as their diode properties are good? Common ground recommended?

What tools are you using to diagram this?

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halley
 
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Re: MiniPOV as a generic sequencer?

Post by halley »

Answering my own question, it looks like the schematic you drew came from EAGLE (http://www.cadsoftusa.com/). I'll have to play with it a bit more but after making a simple circuit and PCB for practice, I find their idea of user interface to be very cumbersome. I found on their site the ATmega8.lbr file required to include some ATMEL controllers used by MiniPOV and Arduino applications.

A friend called your two-transitor stepup technique a Darlington Array, and suggested this link for a single package that supports multiple such arrays: http://www.allelectronics.com/make-a-st ... Y/-/1.html Before I use such a package, I need to find out the current my solenoids will need, to see if the small package can sink it without damage or overheating.

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opossum
 
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Re: MiniPOV as a generic sequencer?

Post by opossum »

EAGLE schematic

The ULN2003 will get quite hot with as little as 100 mA per output. It is not a direct substitute for the transistors shown in the schematic.

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