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/Develop/Hardware/Projekte/RS232 adapter -> 3-pin header with OpAmp/ |
| k1.spdns.de / Develop / Hardware / Projekte / RS232 adapter -> 3-pin header with OpAmp / |
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|
/Develop/Hardware/Projekte/RS232 adapter -> 3-pin header with OpAmp/ |
| k1.spdns.de / Develop / Hardware / Projekte / RS232 adapter -> 3-pin header with OpAmp / |
Last updated: 2011-02-10
Questions & comments to Kio
The Adapter is powered from RTS and DTR of the RS232 connector. It provides RxD and TxD but no hardware handshake.
The board is double sided but should be suitable for home-etching.
Values are choosen for 8 .. 12V signal levels. The adapter should work if attached to a real RS232 port, e.g. a PC port, but should not be used to attach to an RS232 port which is driven by a MAX232 or similar.
LED1 must be present for the adapter to work! LED1 and diode D5 must be choosen so sum up to 2.0 Volt. All diodes may also be of Shottky type.
The exact value of the resistors is not important. But R1/R4 must equal to 1:4 approximately and R4/R3 must be in range 1:4 to 1:3, around 1:3.3 probably working best.
The dual OpAmp should be of a low power type for a supply voltage of up to ±15 Volt or more.
Faster OpAmps allow higher transmission speeds.
RTS and DTR must be driven to different polarity for the adapter to work. Then both LEDs are lit to indicate operational state. Basically you have to disable hardware handshake in your terminal program and set RTS and DTR to different state manually. Use a terminal program which allows this!
It might be possible to extend the design to support the hardware handshake lines. But then the power supply for the quad OpAmp will be tricky: You'll have to assert that RTS and DTR always toggle to opposite polarity.
It seems that even many (most?) PC main boards only supply ±8 Volt with high impedance so that the supply voltage for the OpAmps drop below usable value. And terminal programs which allow you to set RTS and/or DTR are more rare than expected. The only one i have found is HTerm for Windows and Linux. (Which does not mean there are more out there.) This makes this adapter not very useful in general.
| Name | Letzte Änderung | Länge | |||
|---|---|---|---|---|---|
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Board 2.1 components.pdf | 2010-03-04 17:20 | 18968 | ||
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Board 2.1 rear.pdf | 2010-03-04 17:20 | 34087 | ||
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Board 2.1 top.pdf | 2010-03-04 17:20 | 35502 | ||
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part list.txt | 2010-03-06 12:06 | 246 | ||
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RS232 2.1 - 2 Nutzen.brd | 2010-03-04 17:21 | 25669 | ||
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RS232 2.1.brd | 2010-03-04 16:28 | 19754 | ||
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RS232 2.1.s#1 | 2010-03-04 16:28 | 53571 | ||
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RS232 2.1.sch | 2010-03-09 17:31 | 53571 | ||
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RS232 Adapter 2.1 Board.png size: 863 × 518 |
2010-03-04 16:28 | 52223 | ||
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RS232 Adapter 2.1 Circuit.png size: 878 × 441 |
2010-03-04 16:28 | 25500 | ||
 |
RS232 Adapter v2.jpg size: 433 × 718 |
2010-03-12 13:45 | 149516 |
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