I'm wondering if I am approaching this project correctly. I want to have independent control over 64 incandescent 6v light bulbs so I can replicate the start-up and play sequence of lights on a 1979 Paragon pinball table made by Bally.
This will be my first major project.
Should I use the setup pictured below with PropWash's 8x8 Switch Matrix and two Shift Registers, in combination with two of CrossRoad's 32 Channel MOSFET Driver boards?
Or should I just link up 8 Shift Registers and forget the Switch Matrix?
thegr8revealing:
I’m wondering if I am approaching this project correctly. I want to have independent control over 64 incandescent 6v light bulbs so I can replicate the start-up and play sequence of lights on a 1979 Paragon pinball table made by Bally.
This will be my first major project.
Should I use the setup pictured below with PropWash’s 8x8 Switch Matrix and two Shift Registers, in combination with two of CrossRoad’s 32 Channel MOSFET Driver boards?
Or should I just link up 8 Shift Registers and forget the Switch Matrix?
So,
What is wrong with using CrossRoads 32 Channel MOSFET Driver boards directly?
If you connect two of his boards, all you have to do to control 64 DC loads is:
#define SSPIN 10 // Arduino pin connected to SSPIN of the MOSFET board.
uint8_t liteStatus[8];
digitalWrite(OEPIN,HIGH); // shut off all lights. Not actually needed
digitalWrite(SSPIN,LOW); //Actual latch pulse when goes high
for(uint8_t i=0;i<8;i++){
SPI.transfer(liteStatus[i]);
}
digitalWrite(SSPIN,HIGH); // latch current state of shift registers into output latches.
digitalWrite(OEPIN,LOW); // enable all MOSFETS,
That 8x8 matrix board is a SWITCH connection board. It cannot control CrossRoads’s MOSFET boards.
Are you set on incandescent lighting? If you switch to LEDs you could use 8 TPIC6B595 shift registers chained together. They will sink a current of up to 150mA per output which will give you something pretty bright with high intensity LEDs but not so bright with incandescent. From memory you can get them for around $1 each and it's probably a lot less wiring than the transistor approach. I've used them with great success on an LED scoreboard with the LEDs being visible in daylight from the centre of a cricket pitch.
chucktodd:
So,
What is wrong with using CrossRoads 32 Channel MOSFET Driver boards directly?
If you connect two of his boards, all you have to do to control 64 DC loads is:
#define SSPIN 10 // Arduino pin connected to SSPIN of the MOSFET board.
uint8_t liteStatus[8];
digitalWrite(OEPIN,HIGH); // shut off all lights. Not actually needed
digitalWrite(SSPIN,LOW); //Actual latch pulse when goes high
for(uint8_t i=0;i<8;i++){
SPI.transfer(liteStatus[i]);
}
digitalWrite(SSPIN,HIGH); // latch current state of shift registers into output latches.
digitalWrite(OEPIN,LOW); // enable all MOSFETS,
That 8x8 matrix board is a SWITCH connection board. It cannot control CrossRoads's MOSFET boards.
Chuck.
I suppose I was thinking that trying to run an 8x8 matrix switch board with code similar to running an 8x8 LED board would make it easier to code custom patterns and loops into the code?
1001010
0001001
0010010
1010110 etc… It seemed easier coming from a non-coding background.
I’m having trouble imaging what the code will look like driving straight to the MOSFET boards if I want to have bulbs 1-10 count up, while simultaneously having bulbs 49-65 flash on/off, and bulbs 33-38 flash at a different rate, for example.
davidrh:
Are you set on incandescent lighting? If you switch to LEDs you could use 8 TPIC6B595 shift registers chained together. They will sink a current of up to 150mA per output which will give you something pretty bright with high intensity LEDs but not so bright with incandescent. From memory you can get them for around $1 each and it's probably a lot less wiring than the transistor approach. I've used them with great success on an LED scoreboard with the LEDs being visible in daylight from the centre of a cricket pitch.
I was pretty set on having them run the bulbs, they burn so warm in color and all.
TomGeorge:
If they have to be globes, what is their current rating?
Tom...
If I recall correctly they're 0.3A per bulb. I'm looking at roughly a 30amp DC power unit for all of the lights. There's roughly 110 lights all together, of which only about 64 do anything but stay on.
Leds will last a LOT longer (change less often) and draw about 10% as much current. You should be able to find "warm white" leds or could put a bit of colored plastic "filter" over plain white leds.
Wawa:
? Two bulbs in series is twice the voltage, but the same current.
Leo..
On that 12V you posted, the 12V bulb uses half the current. Same 12V with two 6V bulbs in series, same amps as the 12V bulb with 12V supply. Kirchhoff's current law, the bulbs use the same current, each gets 6V drop but it's the same current for two bulbs hence half what a 6V bulb run at 6V uses for one bulb.
I think the primary problem was the switch current of the chips (TPIC6*595), not the overall current of the project.
12volt/100mA or even 24volt/50mA is a lot easier on the chip than 6.3volt/250mA.
Leo..
Wawa:
I think the primary problem was the switch current of the chips (TPIC6*595), not the overall current of the project.
12volt/100mA or even 24volt/50mA is a lot easier on the chip than 6.3volt/250mA.
Leo..
davidrh:
Check the datasheet and I think you will find it can handle 50V.
Thanks David! Seeing it can handle 350mA continuous, it should have no trouble pushing 6V at 0.25A to these bulbs. Though I could use a less powerful power supply if I went 12v.
