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| Need help to understand the circuit pls. |
| (1/1) |
| Chriss:
Hi! I trying to understand a part of this circuit: but have some problems to understand for what is the: D1 or D2 and C1 or C2 and why are the R2 and R6 connected to Ub=12V? Especially I'm interested in the C1 or C2 cap's, why they are in series with the B of the T1 or T2? And the R2 or R6 why that is needed? Thank you. My best regards. |
| T3sl4co1l:
R2 and R6 don't seem to be very useful; the transistors will only turn on when the input pins are driven with more than about 5V peak to peak. Tim |
| SiliconWizard:
This is probably some adapter made to be plugged to RS232 ports. Pins 4 and 7 are DTR and RTS signals, and are typically +/-5V to +/-12V signals. The diode is there to clamp negative voltages since as said above, the input signals can go as low as -12V. The capacitor is there to form a monostable multivibrator. The output pulse (open collector) will have a fixed duration as long as the input pulse (positive) is longer than the time constant. A common trick to ensure a fixed pulse duration here, since it's probably meant to be driven from a PC's RS232 port and the timings of the DTR/RTS signals can't be accurate. |
| Chriss:
Yes, the circuit is an adapter driven from a PC RS232 port. Thank's for that nice explanation. My best regards. |
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