| ??? 03/31/13 16:28 Read: times |
#189591 - Wrong circuits in Mazidi's "8051 Microcontroller....." |
The relay driving circuit (Fig 17-2 in the Indian 2nd edition) in the motor control chapter is wrong.
There is a pullup resistor shown at the pin. During reset when the pin unable to sink current, the pullup will switch the transistor on and hence the relay. The correct way is a pull down to prevent spurious switching of relay, and a darlington if the drive from the pin is insufficient. Same mistake is repeated for the stepper motor, where each ULN input has a pullup (Fig 17-9 in the Indian edition), so at reset, all the motor coils will switch on. |
| Topic | Author | Date |
| Wrong circuits in Mazidi's "8051 Microcontroller....." | 01/01/70 00:00 | |
| I wouldn't expect too many comments | 01/01/70 00:00 | |
| my most painful "textbook experience" | 01/01/70 00:00 | |
| RE: "that book probably isn't widely popular outside India" | 01/01/70 00:00 | |
| Is it possible that one institution or teacher is the cause? | 01/01/70 00:00 | |
| Probably the author's own institution? | 01/01/70 00:00 | |
| The reason for my post | 01/01/70 00:00 | |
Have you fed-back to the authors? | 01/01/70 00:00 | |
| clicking relays | 01/01/70 00:00 | |
| Website - contact here? | 01/01/70 00:00 | |
| More problems with that book | 01/01/70 00:00 |