Building Your Own JP1.2/3 Interface for a Serial Port
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Tommy Tyler
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Building Your Own JP1.2/3 Interface for a Serial Port
New schematics (alas, no construction details) and trouble-shooting information have been posted here.
which resistor and capacitor?
Thanks a lot for the schematics. I'd like to build it but I'm not shure about
the capacitor and resistors. The drawing is a bit hard to read.
Just want to clarify figure 2:
C1 is 0.1µF (Zero is hard to read)
R1, R3, R5 4.7K
R2, R4 47K (or is it 4.7 and the points are missing?)
Just curious: why does figure 1 don't need a capacitor?
Thanks a lot
Thilo
the capacitor and resistors. The drawing is a bit hard to read.
Just want to clarify figure 2:
C1 is 0.1µF (Zero is hard to read)
R1, R3, R5 4.7K
R2, R4 47K (or is it 4.7 and the points are missing?)
Just curious: why does figure 1 don't need a capacitor?
Thanks a lot
Thilo
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Tommy Tyler
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- Posts: 411
- Joined: Sun Sep 21, 2003 11:48 am
- Location: Denver mountains
Those schematics are REALLY hard to read, terrible. Sorry for that. I just posted a new, easier to read version. Take a look.
As for the 0.1MFD capacitor, either the discrete transistor version or the IC version will work just fine with or without it. It's very common design practice to put a bypass capacitor on the Vcc line for high speed ICs, and I probably did it out of force of habit.
As for the 0.1MFD capacitor, either the discrete transistor version or the IC version will work just fine with or without it. It's very common design practice to put a bypass capacitor on the Vcc line for high speed ICs, and I probably did it out of force of habit.
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Kevin Timmerman
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JP1 Flash interface using digital transistors. Minimal parts for small size and quick construction.
Digital transistors have a built in resistor divider network that allows them to be directly driven by digital voltage. The reverse BE breakdown is 10 volts, so RS-232 can be used directly on the base (charge pump transcievers output +/- 9V). An additional ordinary NPN is used to present a high impedance on the remote's tx line to allow the remote to operate normally with the interface connected.
Digital transistors have a built in resistor divider network that allows them to be directly driven by digital voltage. The reverse BE breakdown is 10 volts, so RS-232 can be used directly on the base (charge pump transcievers output +/- 9V). An additional ordinary NPN is used to present a high impedance on the remote's tx line to allow the remote to operate normally with the interface connected.