Electronics > Beginners
Power filter/capacitor board for custom build pinball machine
Raymond175:
Hi all, I'm Raymond and I just joined this forum!
I'm in a very long running project (several years) to build a custom pinball machine from the ground up, which includes woodworking, photoshopping, software development, electronics, etc. I'm a software developer and I'm very eager to learn everything that is needed to complete my project.
Currently I'm facing a power issue in my flipper circuit. As soon as one of my flipper fires, my power supply will "shut down" because of the short circuit protection due to the sudden draw. Therefore I need add a power filter board or capacitor board to "buffer" and offload the power supply. I can buy ready-to-use boards for pinball machines online, but I want to build/design it custom and add more functionalities later, like a coin door interface (which cuts high voltage when the coin door is open) and a 48V to 5V step down convertor (to power my Arduinos via the same power supply).
Now I have very basic knowledge of electronic engineering and basic knowledge of components. And with some logical reasoning I can come quite far with designing my own circuit boards, but my main problem is that I have no clue on figuring out which brand or model of certain electronic components to use and why...
What components I think I'll need to create such a board:
* Connector pins (and cable connectors) for 48V 6.7A power supply
* Capacitors
* Thermistor (to prevent the capacitors from triggering the short circuit protection)
* Multiple power rails
* High voltage LED(s) (for visually indicating that the capacitors are charged as well as draining them)
* Connector pins (and cable connectors) for supplying other components (like the flippers) of power and ground via one of the power rails
* Fuse holders and fuses for protecting the power supply (if needed?)
My questions:
* Do I need any more components?
* How to decide which connector pins to use for 48V 6.7A? Which can also be easily (dis)connected but will stay connected when in use
* How to decide which and how much capacitors to use? A board I saw online had three 8200uF 63V 85C capacitors
* How to decide which thermistor to use?
* How to decide which LEDs to use?
* How to decide which type of fuse holders and which type of fuses to use?
Components:
* Power supply: Mean Well, SP-320-48
* Capacitor: Cornell Dubilier, SLPX822M063H5P3 (?)
Thanks in advance for any reply!
Raymond
PS1: The power filter board that I used for inspiration can be found here:
http://docs.missionpinball.org/en/dev/hardware/fast/power_filter.html
PS2: The pinball machine I'm trying to build is a copy of the Tales Of The Arabian Nights (TOTAN) of Williams:
Kjelt:
Just my two cents
For the relais and coils you actually don't want a switch mode power supply with overvoltage and overcurrent protection.
Just use what the 50s to 90s pinnballs used, a beefy transformer with beefy rectifier and fat electrolytic capacitors. The coils don't care if the unloaded voltage is a couple of volts to high as long as it can quickly draw current and won't choke on the reverse emf voltage.
That is what probably is happening. If you release the voltage to a powerfull coil it will try to keep that current going and it will raise the voltage. To protect you have a diode across the coil. You do have the diode across the coil close to the coil do you?
When a modern smps detects that overvoltage it can shut down. Even when it happens too often it can damage the smps.
The good news powerfull transformers are not that wanted anymore so you can buy them for the copper price. Only the electrolytics might be expensive so try to find good 2nd hand A brands.
floobydust:
Sometimes you keep a flipper up, to catch a ball or poke it.
Pinball machines had a set of contacts on the flipper, so full voltage to get it moving fast and then when the flipper is almost up, switches to a lower holding voltage so the coil does not burn up.
Raymond175:
--- Quote from: floobydust on May 28, 2019, 08:11:11 pm ---Sometimes you keep a flipper up, to catch a ball or poke it.
Pinball machines had a set of contacts on the flipper, so full voltage to get it moving fast and then when the flipper is almost up, switches to a lower holding voltage so the coil does not burn up.
--- End quote ---
The problem is not in the flipper circuit (or coils), but in the sudden draw of power/current by the flipper circuit when they get activated. The coils indeed have 2 separate windings, one large for the powerfull kick an one small for holding the flipper up. This all works fine and are actual original new flipper components. My problem is the sudden draw, which can be from one, two (e.g. flippers) or even six (flippers, kickers, magnets, multiball, etc.) high voltage coils at a time.
Raymond175:
--- Quote from: Kjelt on May 28, 2019, 08:01:31 pm ---Just my two cents
For the relais and coils you actually don't want a switch mode power supply with overvoltage and overcurrent protection.
Just use what the 50s to 90s pinnballs used, a beefy transformer with beefy rectifier and fat electrolytic capacitors. The coils don't care if the unloaded voltage is a couple of volts to high as long as it can quickly draw current and won't choke on the reverse emf voltage.
That is what probably is happening. If you release the voltage to a powerfull coil it will try to keep that current going and it will raise the voltage. To protect you have a diode across the coil. You do have the diode across the coil close to the coil do you?
When a modern smps detects that overvoltage it can shut down. Even when it happens too often it can damage the smps.
The good news powerfull transformers are not that wanted anymore so you can buy them for the copper price. Only the electrolytics might be expensive so try to find good 2nd hand A brands.
--- End quote ---
The whole flipper circuit are original new flipper mechanics, which indeed do have the flyback-diodes between the high and low windings of the coils. But this all works fine, my problem is really the sudden draw, which can be from one, two (e.g. flippers) or even six (flippers, kickers, magnets, multiball, etc.) high voltage coils at a time.
This actual power supply that I'm using was recommended by the pinball community. I'm aware of the old power supplies used in the original pinball machines, but these are actually very hard to get, as they seem to not being manufactured anymore.
But since I'm also going to power so much more than only coils, think of the microcontrollers (Arduinos), lighting, backsplash, display, etc. having this type of power supply with actual protection seems logical to me.
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