Quantcast

Ignition system for Farm Boy

Help Support HMEM:

74Sprint

Well-Known Member
Joined
Apr 21, 2013
Messages
66
Reaction score
20
Location
Winnipeg, Canada
Rudy the problem with your circuit cutting out at higher voltages is that you are grounding out the signal output with the points. I have and use the A1120EUA so I have some experience with it. The A1120 has a built-in voltage regulator and short circuit protection control, the 2 are seperate. The circuitry can provide up to 25ma of current continuously and will trip at 30ma according to the data-sheets. The signal out was never designed to be grounded out, this would put it into a short circuit condition. Like most over current protection it is a latching design and will not reset until the power has been removed and turned back on but, if the condition remains it will lockout again. I don't know the reason for using both a Hall-Effect and points, it should be one or the other.

If your going to use the circuit the way you have it then add a resistor between the points and the Hall-Effect signal as a pull-down resistor that limits the current also then use this formulae V/I=R or properly E/I=R which is 12/0.025 = 480 ohms, 6/0.025 = 240 ohms and so on. I haven't looked at the rest of the circuit I'll do that later and get back to you.

I found if your going to use 555 timers and make a buzz coil and have it work properly you need 3 x 555 circuits. 1 to work as a variable oscillator and the other two to work as what is know as a one-shot mulivibrator. The one-shot circuit can be set up as a non-retriggerable so it gives one pulse out for one pulse in and will not except another in until the first is done, good for debouncing points at high RPM. It will not stay on because you can set the pulse wide to the coil circuit.

I'm making a line of small ignition systems soon and at a price point that I think everyone will like in kit or assembled. The buzz coil is the next design I'm working on. I need to make money so I can buy equipment.

Gnite

Ray
 

Rudy

Well-Known Member
HMEM Supporter
Joined
Apr 20, 2017
Messages
263
Reaction score
201
Location
Norway
Rudy the problem with your circuit cutting out at higher voltages is that you are grounding out the signal output with the points. I have and use the A1120EUA so I have some experience with it. The A1120 has a built-in voltage regulator and short circuit protection control, the 2 are seperate. The circuitry can provide up to 25ma of current continuously and will trip at 30ma according to the data-sheets. The signal out was never designed to be grounded out, this would put it into a short circuit condition. Like most over current protection it is a latching design and will not reset until the power has been removed and turned back on but, if the condition remains it will lockout again. I don't know the reason for using both a Hall-Effect and points, it should be one or the other.

If your going to use the circuit the way you have it then add a resistor between the points and the Hall-Effect signal as a pull-down resistor that limits the current also then use this formulae V/I=R or properly E/I=R which is 12/0.025 = 480 ohms, 6/0.025 = 240 ohms and so on. I haven't looked at the rest of the circuit I'll do that later and get back to you.

I found if your going to use 555 timers and make a buzz coil and have it work properly you need 3 x 555 circuits. 1 to work as a variable oscillator and the other two to work as what is know as a one-shot mulivibrator. The one-shot circuit can be set up as a non-retriggerable so it gives one pulse out for one pulse in and will not except another in until the first is done, good for debouncing points at high RPM. It will not stay on because you can set the pulse wide to the coil circuit.

I'm making a line of small ignition systems soon and at a price point that I think everyone will like in kit or assembled. The buzz coil is the next design I'm working on. I need to make money so I can buy equipment.

Gnite

Ray
Ray, thanks for your useful input! I'll test it. I use hall sensors and just put the point in there for I guessed it would be the same. However, I will put in the resistor as you point out.
Like your idea of making ignition products. I did this on the corner of my lab bench. I do make a living out of hardware development and there is a huge gap between a on time hobb project and a commercial product.
Rudy
 

simonbirt

Member
Joined
Feb 15, 2020
Messages
21
Reaction score
5
Rudy....the ignition Simon is using is a buzz unit also with cut out if no pulse detected.

Simon...you show the diode in series with your LED as a zener diode but quote as a 1N4003 which is a standard diode.(D1)
Connection you show as a zener i.e. reverse which is correct but a standard diode will not conduct in that configuration in normal operation.
Do you have a clear photo of your completed circuit and of the finished pc board, just to clarify what you have done.

Cheers Jorgo
[/Q

Hello Jorgo,

Here are the pictures. I have corrected the symbol on the schematic to show a normal diode.

Regards,

Simon

UOTE]
IMG_4826.jpeg

IMG_4827.jpeg
 

bluejets

Well-Known Member
Joined
Apr 22, 2014
Messages
282
Reaction score
100
Possible to show the schematic you have there,,?
You say you have corrected the drawing to show a "normal" diode....just curious what you have actually done.
I do not see any band or other marking on the device you have in series with the LED.
Others may be interested in your pcb file as well.
 

Latest posts

Top