Hi everyone,

I have built an LED chaser circuit with 7 LEDs as outputs.

I want to modify the circuit by making it a bit more powerful so the LEDs shine bright and then exchanging each LED for a coil of copper and this is where i hit the problem.

So far i have added a darlington pair to each output to bust the current and then replaced an LED in the centre of the 7 with a copper coil as i power up the circuit the lights flow as normal until they reach the copper coil, then the circuit stops?

Can anybody tell me why the cycle will not complete?
( I have enclosed a basic diagram that i started with as i can not upload any pictures at present sorry) also i have spotted the mistake on the 4017 as the pin next to 8 is meant to be 13 not 3.

 

What is the copper coil supposed to do???

It would appear as a dead short if it replaces the LED, which shorts the power supply, pulls the supply voltage down, and resets the counter???

 

Latchup would be my first guess. What makes you think a copper coil is in any way equivalent to an LED? They don't produce light. They have a very low impedance. What were you thinking?

 

What is the copper coil supposed to do???

It would appear as a dead short if it replaces the LED, which shorts the power supply, pulls the supply voltage down, and resets the counter???

Doesn't R2 @ 100 Ω provide a wee bit 'o protection?

 

Doesn't R2 @ 100 Ω provide a wee bit 'o protection?

I wanted the coils to produce a magnetic field, one after another as i have an idea of a project to build if i can do so.
Is there a way i can accomplish this please?

(I am not an electrician or anywhere close i just have ideas and would like to see if some work).

Thank you for your reply.

 

Doesn't R2 @ 100 Ω provide a wee bit 'o protection?

No. A copper coil is going to short the outputs of the 4017. When one output is trying to go HIGH, all the current will flow into all the other outputs which are sinking current. You are creating a dead short across the power supply through the outputs of the poor 4017.

 

OK, I see that now.

 

No. A copper coil is going to short the outputs of the 4017. When one output is trying to go HIGH, all the current will flow into all the other outputs which are sinking current. You are creating a dead short across the power supply through the outputs of the poor 4017.

Thank you for your reply.

Would you know of a a circuit that would fire 7 copper coil outputs one after another please?

 

What is the resistance of the coil?
What is the voltage and current each coil needs?

 

I wanted the coils to produce a magnetic field, one after another as i have an idea of a project to build if i can do so.
Is there a way i can accomplish this please?

(I am not an electrician or anywhere close i just have ideas and would like to see if some work).

Thank you for your reply.

As MrChips pointed out you have to consider each output of the 4017 as a separate and independent circuit. It sorta works with diodes because they only allow current to flow in one direction. The proper circuit would be be one resistor and one LED per 4017 output. If you want a coil to replace the LED you need to increase the resistor to limit the current. Keep in mind that a 4000 series CMOS device cannot supply very much current. Look in the datasheet for parameters Ioh and Iol. They refer to the current with the output high and the current with the output low. Will a couple of milliamps create enough of a magnetic field for your purposes.

 

As MrChips pointed out you have to consider each output of the 4017 as a separate and independent circuit. It sorta works with diodes because they only allow current to flow in one direction. The proper circuit would be be one resistor and one LED per 4017 output. If you want a coil to replace the LED you need to increase the resistor to limit the current. Keep in mind that a 4000 series CMOS device cannot supply very much current. Look in the datasheet for parameters Ioh and Iol. They refer to the current with the output high and the current with the output low. Will a couple of milliamps create enough of a magnetic field for your purposes.

A circuit that produces a couple of milliamps should work i might have to play around with the size of the coils but i will try anything as this is not working

 

What are you trying to build?

 

Because the the resistance of copper coil is very low as short wire, any other output only connected a led to ground and it as a 9V cross on a 2V or 3V LED.

Do you have the datasheet of copper coil or any infos about the copper coil?
What's the purpose of copper coil?

 

to

Because the the resistance of copper coil is very low as short wire, any other output only connected a led to ground and it as a 9V cross on a 2V or 3V LED.

Do you have the datasheet of copper coil or any infos about the copper coil?
What's the purpose of copper coil?

I need the coils to act like an electromagnet if that helps, but i need them to fire and turn off one after another is there a circuit that would allow me to have 7 output coils?

 

Still no answer.
Do you have the datasheet of copper coil or any infos about the copper coil?
And the questions as MrChips asked in #9?
If you want to get a properly answer then you need to offer the infos what the members asked, otherwise you won't get much help.

 

You can add a bunch of driver transistors.

 

You can add a bunch of driver transistors.

There is no spec of the copper coil, otherwise I will suggest the mosfet, becasue that he want to using it as a electromagnet, so I guess that it will be need a great current.

 

Well, I got the idea presented. After you have the logic in place, "How much current" is only a matter of which transistor(s) to use.

 

Well, I got the idea presented. After you have the logic in place, "How much current" is only a matter of which transistor(s) to use.

Since the frequency of clock is only about 6.8hz, and each coil only working about 0.147 second, so maybe no need to use the mosfet ...

 

You never know. This guy might try some hand wound coils under one millihenry. That's what R2 is about in my drawing. Otherwise, he could short out the power supply fairly quickly.