| ??? 05/28/05 06:45 Read: times |
#94035 - Not working, Erik Responding to: ???'s previous message |
Erik Malund said:
If you connect Vcc - 330 ohms - collector emitter - port pin you only use power when the coupler is on and no derivative I know of pull current to gnd when the pin is high. Erik, When applying your proposal (see below), the transistor is not working. The voltage at the IO pin of the PCF8574 stays low, whether I press the switch or not. 
When using my solution (see below), it works fine. But it also works fine when I remove the resistor, located between the IO pin and the power supply (in fact, the pullup resistor). 
So, is it better/wise/advisable to leave out the pull-up resistor, so that I don't have the loss of power you were referring to, when the transisor is in the off state too? Best rgds, --Geert |
| Topic | Author | Date |
| CNX83: application examples? | 01/01/70 00:00 | |
| HOW | 01/01/70 00:00 | |
| did you find some in a drawer | 01/01/70 00:00 | |
| I know they're quite old... | 01/01/70 00:00 | |
| Better | 01/01/70 00:00 | |
| Schmitt Trigger | 01/01/70 00:00 | |
| nothing wrong - but | 01/01/70 00:00 | |
| Not working, Erik | 01/01/70 00:00 | |
| Pullup Or Not | 01/01/70 00:00 | |
| Additional Comment on Rise Time | 01/01/70 00:00 | |
| Confustion maybe? | 01/01/70 00:00 | |
| Yes, you need on PCF8574 | 01/01/70 00:00 | |
| No hijacking at all!!! ;-) | 01/01/70 00:00 | |
| Walks like a duck? Quacks like a duck? | 01/01/70 00:00 | |
| Yes, I do have quite a few ducks... | 01/01/70 00:00 | |
| Correct? | 01/01/70 00:00 | |
| Correct !! | 01/01/70 00:00 | |
| you must have edited | 01/01/70 00:00 | |
| I didn't do anything... | 01/01/70 00:00 | |
I do not know | 01/01/70 00:00 |