geekhack
geekhack Projects => Making Stuff Together! => Topic started by: Melvang on Fri, 01 July 2016, 22:47:07
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So I got my Kishy built up and got the buzzer working. I then set a key to "EXP Toggle". This key toggles the expansion header on and off for the buzzer/solenoid pins. Now this function works great when using a solenoid, but not so much when using a buzzer out of an IBM. I did some digging over on DT and I found the problem.
Here is a quote from xwhatsit himself, "The problem is the kishsaver buzzer takes three connections, VCC + GND (power) and the control signal. The polarity of the control signal is identical (0V = off, 5V = buzzing), but the problem is the buzzer's internal wiring has a pull-up resistor that pulls it up to 5V when nothing else is pulling it down to 0V. When the expansion header is disabled, power is still supplied (it's just hooked up straight to the main USB VCC + GND), but the control signal is left to float completely (if you have some other thing hanging off there, like a switch, when you're disabled you don't want to intefere with the circuit). The Kishsaver's buzzer circuit pulls it up to 5V and it starts buzzing.
So yep... either the pull-up could be modified into a pull-down (as it is on the solenoid driver board),"
So the question is, can I just take out one of these resistors, and more one connection from 5v to GND, or would it require a redesign? If it would be a redesign, how much of the original parts could be salvaged? Of these, can they all be bought new to have new batches made?
Here are some detailed pics of the board. Resolution warning on these images if you click the expand button after clicking on the images. I shot these with a Cannon 7d at full resolution.
[attach=1]
[attach=2]
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I had a reply all typed up, but then I read your OP and realized you were asking a different question than the one I was answering. Off to think about your question...
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I had a reply all typed up, but then I read your OP and realized you were asking a different question than the one I was answering. Off to think about your question...
Cool cool. Any initial thoughts?
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Was just thinking, if this is going to require a redesign of the board from the ground up, would it be possible to design it with the buzzer, solenoid, and driver circuit for the solenoid all on one board? Ideally, I am thinking put a volume control and selector switch for buzzer/solenoid inside the access hole for the current volume control for the buzzer. Or even possibly, tweak the xwhatsit on the expansion side and the firmware and allow this including volume in the firmware.