| ??? 04/07/05 19:37 Read: times Msg Score: -1 -1 Didn't Search First |
#91200 - Driving 12V Relay W/ 8051 |
I would like to use the 8051 to control two 12VDC relays that will then control a door-lock actuator for a project I am working on. I have two circuits, but am having trouble combining them. Its tough to explain, but I will try:
each of the output pins of PO are first hooked to a 2N2222 transistor (10k pullup transistors are installed for P0). The output of the 8051 runs to the Base of the 2N2222, while the Emitter is connected to ground. My question is then how exactly do I interface this with my relay/door lock circuit? Here is the 8051 circuit I found online: +5 | / R3 ------- / 2N2222 ------ | _____| |___///___ +5v | | B |/ C | load | R2 Micro |<-----------------| ------ | | E ------- | GND The relay/door lock circuit has constant 12V running to pins 87 on each of two relays, while pins 30 on each relay are connected to either lead of the actuator. 87a are both grounded, as well as pin 85 on the "Lock" relay and pin 86 on the "Unlock" relay. Pin 86 on the "Lock" relay should receive one trigger from the 8051, while pin 85 on the other should receive the "Unlock" trigger from the 8051. It looks like this: [IMG]http://img140.exs.cx/img140/2601/relay17b8qc.th.gif[/IMG] I'm having some trouble figuring out exactly what should connect from circuit 1 to circuit 2. I can't figure out where the 5V source to the right of the load should go, or if I need it at all. I would appreciate any tips. |
![[IMG]http://img140.exs.cx/img140/2601/relay17b8qc.th.gif[/IMG]](http://img140.exs.cx/my.php?loc=img140&image=relay17b8qc.gif){kind=link}
| Topic | Author | Date |
| Driving 12V Relay W/ 8051 | 01/01/70 00:00 | |
| Ammended Image Post | 01/01/70 00:00 | |
| that get you nowhere. | 01/01/70 00:00 | |
| A few things | 01/01/70 00:00 | |
| No, that is not so. | 01/01/70 00:00 | |
| an 8751, perhaps | 01/01/70 00:00 | |
| Pull Ups and Base Current | 01/01/70 00:00 | |
| ULN2003 | 01/01/70 00:00 | |
| door lock diagram | 01/01/70 00:00 | |
| One more method... | 01/01/70 00:00 | |
| Why not use 2N7000 | 01/01/70 00:00 | |
| 2N7000 Not Good By Itself | 01/01/70 00:00 | |
| You have a point | 01/01/70 00:00 | |
| FET solution | 01/01/70 00:00 | |
| Elegant? | 01/01/70 00:00 | |
| True.. | 01/01/70 00:00 | |
| It Can Be Small | 01/01/70 00:00 | |
| Zetex | 01/01/70 00:00 | |
| Could it be smaller? | 01/01/70 00:00 | |
| Think so. | 01/01/70 00:00 | |
| Onboard Resistors | 01/01/70 00:00 | |
| Digital transistors | 01/01/70 00:00 | |
Missed | 01/01/70 00:00 | |
| an added note | 01/01/70 00:00 | |
| solved by Allegro | 01/01/70 00:00 | |
| part number for Allegro chip? | 01/01/70 00:00 | |
| take your pick | 01/01/70 00:00 | |
| I missed a few | 01/01/70 00:00 | |
| It was a note :) | 01/01/70 00:00 |