Hi
First the confession bit. The only thing I know about electronics is what I have picked up on the net. I do not have a technical background. I have been making clocks with electromagnetic coils controlled by a slot switch (the switch was designed by a friendly engineer at the Australian National University) for the last 8 years or so.
The problem is that these clocks require a pendulum and I am trying to build a clock that does not require a pendulum and I have been experimenting with a switch to drive clock mechanisms replacing the pendulum with a short shaft or rod.
I am now using a different switch which has a 12f683 chip (instead of the slot switch) to provide 30 impulses to the coil each minute. The resultant EMF attracts an armature on one end of a shaft. The other end of the shaft is used to drive a count wheel. I am experimenting with two coils. One is 16 ohms wound with .5mm wire and the other 30 ohms wound with .3mm wire. The input (regulated) can be varied between 4 to 5 volts but at the moment I am running at 5 volts.
The original transistor in the switch to power the coil is a 2n2222 but it lacked the power to drive anything very much at all. Initially I tried two 2n2222s as a Darlington pair and that certainly improved the output. I even considered a Darlington triple. Instead to tried a Mosfet J538 in another switch and it was an improvement and is driving the clock but I think it needs a bit more power because it does stop from time to time. I have tried to look at Mosfet data sheets to see if there is an alternative to the J538 that will increase the output but they might as well have been written in Swahili. So what I would like to know is if there is an alternative to the J538 to increase the output to the coil. Incidentally (or perhaps not) this switch was designed by a friend and we have been experimenting for a while. He has recently come to the conclusion that including a capacitor between the positive and negative rails may assist by my initial tests are inconclusive.
Sorry to be long winded.
Robert
First the confession bit. The only thing I know about electronics is what I have picked up on the net. I do not have a technical background. I have been making clocks with electromagnetic coils controlled by a slot switch (the switch was designed by a friendly engineer at the Australian National University) for the last 8 years or so.
The problem is that these clocks require a pendulum and I am trying to build a clock that does not require a pendulum and I have been experimenting with a switch to drive clock mechanisms replacing the pendulum with a short shaft or rod.
I am now using a different switch which has a 12f683 chip (instead of the slot switch) to provide 30 impulses to the coil each minute. The resultant EMF attracts an armature on one end of a shaft. The other end of the shaft is used to drive a count wheel. I am experimenting with two coils. One is 16 ohms wound with .5mm wire and the other 30 ohms wound with .3mm wire. The input (regulated) can be varied between 4 to 5 volts but at the moment I am running at 5 volts.
The original transistor in the switch to power the coil is a 2n2222 but it lacked the power to drive anything very much at all. Initially I tried two 2n2222s as a Darlington pair and that certainly improved the output. I even considered a Darlington triple. Instead to tried a Mosfet J538 in another switch and it was an improvement and is driving the clock but I think it needs a bit more power because it does stop from time to time. I have tried to look at Mosfet data sheets to see if there is an alternative to the J538 that will increase the output but they might as well have been written in Swahili. So what I would like to know is if there is an alternative to the J538 to increase the output to the coil. Incidentally (or perhaps not) this switch was designed by a friend and we have been experimenting for a while. He has recently come to the conclusion that including a capacitor between the positive and negative rails may assist by my initial tests are inconclusive.
Sorry to be long winded.
Robert