| ??? 02/10/14 08:37 Read: times |
#190270 - Mostly there Responding to: ???'s previous message |
In the logic high state the AT89C51 lets the pin float (i.e. IOH is omA), so it is just pulled up by both the 10k SIP and the 4.7K of R3. You don't need both, but you do need a sufficiently low resistance to turn Q1 on fully.
The base of Q1 loads the network, which is why you only see 1V at the pin when it's logic high. There is nothing wrong with this. |
| Topic | Author | Date |
| Interfacing 12V relay with AT89C51 | 01/01/70 00:00 | |
| Mostly there | 01/01/70 00:00 | |
| Then what do to avoid loading?? | 01/01/70 00:00 | |
Pin doesn't pull up | 01/01/70 00:00 |