| ??? 02/06/10 09:01 Read: times |
#172939 - Relevance to pushbuttons Responding to: ???'s previous message |
Richard Erlacher said:
One of the problems with solderless breadboards is that they are so fragile, i.e. the circuits built on them are easily disturbed. True - and could be relevant here. Also, the contacts can be quite unreliable - especially after an amount of use. people using them seldom take the physical parameters of the breadboard, i.e. adjacent contact capacitance, resistance, inductance, etc. Probably mostly not relevant here, apart from the contact resistance point - see above. At well-below audio frequencies, which is what the things were designed to support, solderless breadboards should work pretty well. A pushbutton (including its bounce) is "well below audio" - so a solderless breadboard should work "pretty well" in the application at hand. (subject to the limitations already noted). At frequencies well above audio, however, those often ignored parameters become a factor. Unlikely to be relevant here. there's no reason to believe, when you build a circuit, that, if you leave it while you go to lunch, that the circuit will be the same when you return. Very true: This is related to the "fragility" already noted - and could be relevant here. Things move around, contacts change in their resistance, capacitance, etc ... not much, of course, but they do change, particularly if the circuit is disturbed. Indeed. And, if the circuit was "marginal" anyway, that could be the difference between working & not. That's why I suggest implementing a proper, reliable debounce in software. I seldom use one, except, perhaps for demonstrating a very simple low-frequency circuit. Such as a pushbutton, perhaps...?! |
| Topic | Author | Date |
| Buttons - Hardware | 01/01/70 00:00 | |
| do double check .... | 01/01/70 00:00 | |
| Debouncing | 01/01/70 00:00 | |
| Have you considered that it could simply be the "breadboard" | 01/01/70 00:00 | |
| I (dis)agree | 01/01/70 00:00 | |
| Relevance to pushbuttons | 01/01/70 00:00 | |
| Consider the objective | 01/01/70 00:00 | |
| Agreed | 01/01/70 00:00 | |
| that's why there's so fluid a definition for "working" | 01/01/70 00:00 | |
| PCB's to match the contact arrangement on a "breadboard" | 01/01/70 00:00 | |
| Not exactly ... | 01/01/70 00:00 | |
| Solved: | 01/01/70 00:00 | |
Never discharge a cap directly by a switch! | 01/01/70 00:00 |