| ??? 12/10/07 01:40 Read: times |
#148022 - Memory relays and reset problems Responding to: ???'s previous message |
Raghunathan said:
...<snip> And the other option for such long held switched requirements is to use a solenoid with mechanical "detent" facility - it just needs a 24V dc pulse lasting a second or so for shifting and once the spool shifts, it is held there by a spring loaded detent. ( Also called "memory valve" ! )
Raghu I have 50 memory relays in my shelf. I am also quite sure those will stay there unless I find some useful use for them - fishing lures - maybe. Those relays are toggled by applying a voltage on them. With reverse voltage they switch off and with straight voltage they switch on. They keep their state indefinitely. So on POR one has to "remember" to switch them to a known state. I assume that the solenoids You are talking about need a short pulse to release their grip. The problem with this type of solenoids and relays is that they may be on when the system is powered down. So when powering up the relays might already be on causing all sorts of funny things to happen. Ordinary relays are plain and simply OFF when then system comes up. No hassle. |
| Topic | Author | Date |
| Looking for a one of six selector chip | 01/01/70 00:00 | |
| HMM | 01/01/70 00:00 | |
| sounds like you need a PAL | 01/01/70 00:00 | |
| have you looked at 74HC237 with a 1 Hz clock? | 01/01/70 00:00 | |
| Oh-Oh-Use-Mcu | 01/01/70 00:00 | |
| Driving is easy. | 01/01/70 00:00 | |
| It is dead easy but ... | 01/01/70 00:00 | |
| Current, not voltage | 01/01/70 00:00 | |
| Practise and Theory | 01/01/70 00:00 | |
| I decided to settle for the MCU | 01/01/70 00:00 | |
| Memory relays and reset problems | 01/01/70 00:00 | |
| So ... you\'re using a latching relay? | 01/01/70 00:00 | |
| Example of a solenoid driver | 01/01/70 00:00 | |
| chip driver | 01/01/70 00:00 | |
| Yes, that's the kind of thing | 01/01/70 00:00 | |
| No, voltage, not current! | 01/01/70 00:00 | |
| AC solenoids | 01/01/70 00:00 | |
| Thread morphing... | 01/01/70 00:00 | |
PLC | 01/01/70 00:00 | |
| trivial, maybe, but why not use a 'trivial' uC | 01/01/70 00:00 | |
| Trivial microcontrollers | 01/01/70 00:00 |