Magnetic lock

[mark Easterling]

I am using an 18m2 with a keypad to open and close a magnetic lock. When I turn on B.4 which controls the Lock nothing else works properly on the circuit, if B.4 is not turned on everything works.

How can I solve this problem?
Thanks,
Mark

 

[Technoman]

A circuit diagram might help in finding the cause.

 

[Buzby]

A circuit diagram, including details of the power supply arrangements. A photo might help as well.
It definately sounds like the magnetic lock is sucking the power down, and the PICAXE is being starved.

This assumes of course that the fault only appears when you physically drive the lock.
If the fault occurs when you run in the simulator, then it's a software problem, so please post your code as well.

 

[john2051]

Hi Mark, without a diagram it is not simple. However from my own experiences and from reading many posts on here, the usual culprits are lack of decoupling capacitors, lack of back emf diodes across things like the lock coil and the lock driver transistor or fet not big enough for the task.
regards john

 

[hippy]

When I turn on B.4 which controls the Lock nothing else works properly on the circuit, if B.4 is not turned on everything works.

This sounds like the lock is dropping the supply voltage or drawing excess current though the PICAXE which is causing it to reset or fail when B.4 is activated, or it could be back EMF causing an issue as suggested.

If there is no drive transistor or FET between the B.4 and the lock that would be my guess as the likely culprit; the pin simply not able to produce the current to drive and activate the lock.

One test would be to see if everything keeps working when B.4 is activated with the lock replaced by an LED+R.