| ??? 01/09/06 13:36 Modified: 01/09/06 13:40 Read: times |
#106888 - Not designed for switching purpose Responding to: ???'s previous message |
Prahlad said:
The common anodes are multiplexed the sourcing to common anodes is done using BC557B transisitors bases of which are connected to Port 2 of micro. BC557B is not designed for such switching tasks. Its collector emitter junction is two high ohmic. Maximum collector current is only 100mA and peak collector current is only 200mA. Try to use BC327 instead. Maximum collector current is 800mA and peak collector current is 1A. Collector saturation voltage is much much lower resulting in less heat to be dissapated by the transistor. Kai |
| Topic | Author | Date |
| Sourcing current to commong anode SSD. | 01/01/70 00:00 | |
| Not designed for switching purpose | 01/01/70 00:00 | |
| maybe even better | 01/01/70 00:00 | |
| Thanks for your reply erik. | 01/01/70 00:00 | |
| Oops I made serious design mistake. | 01/01/70 00:00 | |
| saturation required | 01/01/70 00:00 | |
| Try BC188 or BC640 | 01/01/70 00:00 | |
| Google fails | 01/01/70 00:00 | |
Indian creation | 01/01/70 00:00 | |
| Base resistors | 01/01/70 00:00 | |
| ULN2003 & ULN2803 | 01/01/70 00:00 | |
| Second sourced | 01/01/70 00:00 | |
| but thre aer newer "equivalents" | 01/01/70 00:00 | |
| try toyolite | 01/01/70 00:00 |