In the previous update on the Solenoid Power Driver I explained that I had submitted the new PCB design to manufacturing, and also ordered new transistors.
The PCB's came in and they look marvelous! These prototype PCB's were proudly manufactured in the USA, though I'm not sure where ExpressPCB conducts their full-scale production runs. This was my first time using ExpressPCB, and I am very pleased with the results.
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| All the various components fit perfectly onto the ExpressPCB manufactured prototype PCB. |
The new design is revision 3.0 of my Pinball Solenoid Power Driver, and is optimal for use with the LED-Wiz as the controller. Compared to my original design, the new circuit board is not only smaller, it upgrades all outputs to High Power circuitry, and adds fuses for each output as well as the main power source.
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| My original prototype (brown) had 4 High Power and 12 Low Power circuits, and no fuses. My new design is much smaller, yet it provides 16 High Power outputs. Every output is fused, along with a separate fuse for the power supply. |
The new transistor came in as well, and it... was promptly fried. Faster than corn in hot oil, these transistors popped as soon as a solenoid load was introduced. Lowering the voltage to 25V from the normal 50V, these transistors worked just fine, but the solenoids fired weakly.
So now I had a new challenge, to find an even better transistor, but in the same package with the same pinout, and electrically compatible with my freshly milled PCB boards. The task seemed impossible.
I'm happy to announce that I was successful in my search. Instead of trying yet another BJT transistor, I went with a Power MOSFET transistor.
Power MOSFETs are different from BJT transistors in that MOSFET's use a small voltage to control a large current, whereas BJT transistors use a small current to control a large current. Lucky for me, they are available in the same TO-220 package, and the pinout is fully compatible with my existing circuit design.
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| Testing the new Power MOSFET transistor. Worked perfectly each and every time. |
In preliminary testing the Power MOSFET transistor has performed perfectly. From a technical standpoint, this transistor even appears to be superior to the MOSFET that Stern Pinball uses, or at least used at one time. I haven't bothered to research if Stern has chosen different MOSFETs for their more recent games. Not only is my chosen MOSFET capable of handling more power than Stern's counterpart, it also has quicker response times - roughly twice as fast.
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| Now the the PCB is assembled, it's time to do some testing. |
I've soldered up the first PCB, and it will soon undergo performance and endurance testing in the Modern Firepower pinball machine.
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| The new Pinball Solenoid Power Driver v3.0 is small enough to fit snugly on the Modern Firepower playfield. |
Wiring for lighting, and now solenoids, continues. More updates soon...
