| ??? 05/02/05 22:29 Read: times |
#92765 - Check Power Supply & Driving Responding to: ???'s previous message |
Hi!
Have you checked the power? Motors can drain a huge amount of current from the power supply, specially when reving up. Sometimes motors should have a separate supply to eliminate this problem and the noise problem Eric describes. I've seen further over the schematics, and suppose there should be driving transistors connected to the outputs of the uP. I mostly use MOSFET's because they are more "ON/OFF" than regular BJT's. The point here is that a MOSFET (i.e. BS170) will work as a pre-switch for the relay. The solenoid on a relay can make dangerous spikes that some time almost sertenly will destroy the port on the uP. Also remember to alvays put decoupling diodes with inverse polarity over the solenoid (Fly-back diode). The diode will handle most of the spikes generated. I'll send you an example of how to implement the MOSFET's if you are interested. John E. |
| Topic | Author | Date |
| Driving Relays with TPIC6C595 | 01/01/70 00:00 | |
| noise as always | 01/01/70 00:00 | |
| Check Power Supply & Driving | 01/01/70 00:00 | |
| Relay Noise? | 01/01/70 00:00 | |
| Did you get my mail? | 01/01/70 00:00 | |
| Yes | 01/01/70 00:00 | |
| a glaring omission | 01/01/70 00:00 | |
| Not on schematic | 01/01/70 00:00 | |
| please, pretty please | 01/01/70 00:00 | |
| Sorry | 01/01/70 00:00 | |
Jon, it was general | 01/01/70 00:00 |