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  • Joined: 31 Oct 2007
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  • Location: Estonia, Rapla city
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Light phaser schematic
Post Posted: Sun Mar 19, 2017 8:22 pm
I got a light phaser and made a schematic of its circuit.

Maybe it is useful to someone.
LightPhaser3050.png (330.7 KB)
Schematic
LightPhaser3050.png

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Post Posted: Mon Feb 11, 2019 9:49 am
The Sega docs say that the light phaser lowers TH for 20-30us when the raster beam enters it's field of view. Is that edge trigger and pulse duration done in the circuit above?
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Post Posted: Tue Feb 12, 2019 7:12 pm
There seems to be no signal length shaping done in the circuit, whatever comes in is highpass filtered and amplified in successive steps with extra gain at higher freqs in each amplification stage to ensure clean edges.
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Post Posted: Tue Feb 12, 2019 8:51 pm
Interesting, so presumably the high pass filter is to remove any DC offset rather than to remove the actual signal blip itself, and the amplification then makes it more binary shaped? 20us corresponds to about 80 pixels which is certainly bigger than the gun's field of view when close to the screen, but maybe Sega was thinking more of the size at normal distances. Games polling TH seem to do so every 6us or so at best, which may compensate.
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