--Boundary_(ID_QTHSQpmw5Ypw5QB/YELEKg) Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7BIT Peter Peres wrote... >Dave D., have you, or anyone else, tried to operate one or both of the >MAX232x RS232 drivers from its own switching frequency followed by a >doubler or triper to get even higher (or lower) voltage ? I have a project >where I could use 70Vdc at very low power. I think that this will work. >What do you think ? What does the MAX232 spec say about overloading the >outputs ? Afair RS232 allows dead shorts on the outputs indefinitely. >True for MAX232 ? I haven't tried that, Peter, but I don't see why it wouldn't work provided the loading is very light. The MAX232 datasheet says the outputs can withstand continuous short-circuit loads, so that's not a problem. The only possible difficulty I can see is that the internal charge pump switching frequency might be too high for the transmit driver slew rate: on the MAX232A I measured 120 KHz switching frequency. But here's a circuit to try; it might be interesting to see what it does. (You'll have to find diodes/capacitors with sufficient voltage rating.) Dave D. --Boundary_(ID_QTHSQpmw5Ypw5QB/YELEKg) Content-type: image/gif; name=hvpumper.gif Content-transfer-encoding: base64 Content-disposition: attachment; filename=hvpumper.gif R0lGODlhEgIeAYAAAAAAAP///yH5BAEAAAEALAAAAAASAh4BAAL+jI+py+0Po5y02ouz3rz7D4bi SJbmiabqyrbuC8fyTNf2jef6zvf+DwwKh8Si8YhMKpfMpvMJjUqn1Kr1is1qt9yu9wsOi8fksvmM TqvX7Lb7DY/L5/S6/Y7P6/d8BOAP4Af411doKAZ4MEj4EmjgmAB5MrjAeHiJSQIpqQgjyclpshkZ EJp5imph6hfzKbgq4vo4m1prKwFbKiNLiiI7ehss3Fs5A6zb6ctaujjsLHyM3Jr4mgsSnfysXUud PUZZvC0+Tl5ufo6eru4Raq0C6/4Bv04/Z0lrvBrPrl/vDweqRrdlKQZ6+4cQzb19kwxK8+WQYcKJ WnjtAndQFEb+fBQ7IiJ4caPEDYssejzZxdJITSUzliiJTUfLR91MorxJcOUImI50YuDJ8V2ueQ97 gsR5qpkmlz83RuAZaKTSCVAfknRK6t7RbL+2Ir00NRbTC2GfQpWK9cFZn5XSct00kyMvo0LX2r2L N6/evXz7+v17dwXgwYAVET6MOLHiwZFsBuQaVNRXkoLlue0QM0NZCGsrbFZ71rLDnO0UPJbLluxk Dak9i9Z6bayqywyqoh3twPbrocyomjYIW/Lqn5VjC7fKQSdQ5E/JwoxMGfST1l+p+zbOUrbq2VOV O+8ewjoR8TfJcw5/nDnr7wO9c2+Pnov5k/Nzx1+qXRX70xT+lDudX98PAVI0YDjyvGRTdJ5FtN2C 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