Need TTL Cookbook page 171 & 172. 555 timer 2N3055 vintage Electric Fence Charger

crutschow said:

Yes,a smaller R3 resistor will shorten the ON pulse.
Why.?
You appear to be making random changes to the circuit for no particular reason.

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I am learning, to see what is does. I notice online circuit drawings have a whole range of different part values in the same place .1 uf to 100 uf. I always though my 2 year tech school college class was good but now I realize it was a dud. First year was good we had an excellent teacher we learned all the basics. Second year the good teacher quit the new teacher did not teach he said, read the book do problem at the end of each chapter. Lab was building a kit we bought from an electronic supply place. Book was more ohms law circuit math but nothing how to use parts in real circuits. We learned nothing how or why parts work in circuits. 50 years ago it away vacuum tube technology. I had my own workshop at home I learned how to design and build tube circuits using the tube manual date sheet for each tube. I got a job in industrial electronics I never used much of what I learned. I bought a used collect tech book online so far it looks good it is going to take me a while to learn things I would like to know. I hope some day I don't have to ask so many questions. People on this forum have a 50 year head start on me. If I can learn things i don't know I don't need to ask question. At the moment I need lots of help building projects I want to build all i can really do is build circuits I find online or in books, most of them don't work.

gary350 said:

At the moment I need lots of help building projects I want to build all i can really do is build circuits I find online or in books, most of them don't work.

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And yet you tend to refuse to try ones that do work and are proven. Like Chemelec's in post #27 or the one I linked to in post #26.

shortbus= said:

And yet you tend to refuse to try ones that do work and are proven. Like Chemelec's in post #27 or the one I linked to in post #26.

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#26. I don't have any 2N3055 transistors. I was thinking about ordering transistors but was hoping the mosfet will work and I don't need the 2N3055.

#27. say, this higher power unit might kill your animals.

#1. if you read you see it says, high power units kill animals. I have 4 cats & 1 small dog I don't want to kill them.

I double checked and I was right, no 2N3055 transistors. I ordered 10 for $6 from Colorado they will be here May 28. I was right I used all my 2N3055s to repair a 250w amp. This is all the power transistors I have.

I find lots of ferrite beads on transistors in old TVs so i did some reading about what they are used for. EMI suppression, lightning, static, ignition coils. This sounds like what I need. I put 1 ferrite bead on mosfet pin 1 and pin 3. I put 10 ferrite beads on mosfet pin 2. Diode on mosfet pin 2 and 3. 1.3 ohm 2w resistor on B+. I ran the circuit for about 5 minutes it makes a nice 1/16" spark. After 5 minutes 2w resistor was starting to get warmer, room temperature about 72, resistor about 80 degrees. Resistor might need to get larger. I find lots of resistor heat sinks in TVs I think I will put a heat sink on the 2w resistor to see how well it works. Scope shows a nice square wave. I am not seeing any voltage spikes from the ignition coil. I ordered some 2N3055 transistors, I decided not to wait for them to arrive. It is hard to get a good clear photo without the try pod.

Again, your symbol for the Mosfet is missing the arrow that shows if it is N-channel or P-channel. Also, again the symbol is upside down but the pin numbers are correct. Please copy the symbol on the datasheet.

Your D3 1N4007 diode is very slow and does nothing. It would conduct and clamp the pin 2 of the Mosfet from going negative which never happens in that circuit. The inductance of the coil will cause pin 2 to go positive when the Mosfet turns off. The diode does nothing when the pin 2 goes positive.
The Mosfet already has a diode and it is a Zener type that clamps the pin 2 voltage from going too much positive.

audioguru said:

Again, your symbol for the Mosfet is missing the arrow that shows if it is N-channel or P-channel. Also, again the symbol is upside down but the pin numbers are correct. Please copy the symbol on the datasheet.

Your D3 1N4007 diode is very slow and does nothing. It would conduct and clamp the pin 2 of the Mosfet from going negative which never happens in that circuit. The inductance of the coil will cause pin 2 to go positive when the Mosfet turns off. The diode does nothing when the pin 2 goes positive.
The Mosfet already has a diode and it is a Zener type that clamps the pin 2 voltage from going too much positive.

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I remember you said mosfet needs NO diode & its upside down before, and other people were saying, mosfet needs a diode. Someone said, build the proven circuit that was posted but I know proven circuits seldom work. OK I am going to remember this time mosfet does "NOT" need a diode. I have some fast diodes but 1 circuit someone said I should build uses 1N4007 and I just happen to have 1 laying on the work bench so I use it. Tomorrow I remove the diode. Yes I know I left the diode out of the mosfet drawing most drawings do not show it but everyone knows it is there but I did not realize why it is there. I had mosfet drawn upside down before someone else mentioned it and I fixed it, not sure how I got it upside down again. I need to learn correct way to draw mosfet without looking at 1 already drawn. All the circuit needs now is a HV cap on the output of the coil maybe, I need to be careful not to kill small animals this thing shocks me good enough as it is. I need to test all my 1 ohm 5W resistors I hope I can find 1 that is 1.3 ohms.

The circuit has a problem. It did this once before. After running several minutes 555 gets smoking hot and shorts out and that kills the mosfet. I don't understand why 555 gets so hot? I don't understand how bad 555 kills the mosfet? Before 555 goes bad it starts doing random pulses.

gary350 said:

#1. if you read you see it says, high power units kill animals. I have 4 cats & 1 small dog I don't want to kill them.

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Are you going to use the same exact transformer as he did? All you need to use is the switching circuit from either link, some thing that if you build it correctly will work. But then again I have my doubts that can/will happen.

shortbus= said:

Are you going to use the same exact transformer as he did? All you need to use is the switching circuit from either link, some thing that if you build it correctly will work. But then again I have my doubts that can/will happen.

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I know that circuit with the 2N3055 works I built it 40 years ago with a variable resistor KHz control and it still works. The ignition coil works best between 1 and 2KHz. I built a simple 555 circuit for it. I am done with the mosfet circuit wait a month the 2N3055 transistors will be here but I won't be here. We are taking a 1 month trip in the RV.

New parts arrived. Here is the circuit drawing. It works good, it makes a 5/16" spark. I wanted a 2W resistor but only 100 ohm resistor I could find was 5w. Now I need to build it into a neat little box. I knew the 2N3055 will work it works on the circuit I built 35 years ago. Both circuits are the same only difference is, 555 in this circuit is 1Hz fixed the other circuit is variable 100Hz to 5Khz with 50% duty cycle.

Diode D3 keeps shorting out so I left the diode off and circuit has been running good for 30 minutes.

Output of 555 at pin 3 is 10.5v. Output of 555 pin 3 other side of 100 ohm resistor at the 2N3055 base is .56v to .60v. Datasheet for 555 says pin 3 is 225ma. Voltage drop of 10v x .225 = 2.25W with duty cycle of 5% so 2.25W x .05 = .1125w if I have this right I can replace the 5W resistor with a 1/4 watt 100 ohm resistor.

gary350 said:

Diode D3 keeps shorting out so I left the diode off and circuit has been running good for 30 minutes.

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Why would you imagine a tiny 1N4148 would do the job?, you need a much more powerful diode - without it the transistor may be at risk.

And what's with the pointless ferrite beads?. Also C5 and R8 seem rather strange as well?, the high value of R8 means that C5 isn't doing anything.

I changed 100 ohm resistor from 5w to 1/4w tested it 15 minutes & took pictures. I finally got a good pic of a 3/8" spark = about 60,000v with 1/8" is usually considered to be about 20KV. 1/4w resistor is not getting warm with circuit set to make 1 spark per second. I have a good video too.

Your 100 ohm base resistor has about 100mA (10V/100 ohms) in it, not the 225mA maximum allowed output current from a 555. Then its continuous power would be 10V x 100mA= 1W, not 2.25W. With the duty cycle at 5% then it dissipates only 0.05W.

You are lucky to have a sensitive 2N3055 because some of them saturate with only 1A when the base current is only 100mA.

Wait a minute. Your 'scope appears to be set to show 20ms per division and the pulse uses 2.5 divisions then its duration is 50ms and the duty cycle is 20%, not 5%.

It would help if didn't change the circuit parts and design, without understanding what those changes do.
Circuit design by randomly changing things hardly ever results in a good design.

crutschow said:

Circuit design by randomly changing things hardly ever results in a good design.

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Au contraire --

Muntzing: Trial and error electronic circuit design; particularly, "optimization": reducing the parts count by clipping out parts until the circuit stops functioning, putting back in the last part removed, and calling the design complete.

https://en.wikipedia.org/wiki/Madman_Muntz#Muntz_TV

ak

I forget, what is the final purpose of this? Is it really going to be used for a fence? Must be a small, short one, and in an open area with no grass or weeds?

shortbus= said:

I forget, what is the final purpose of this?

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Really? After only 136 posts? tsk tsk tsk Kids these days, no sense of history.

ak

AnalogKid said:

Muntzing: Trial and error electronic circuit design; particularly, "optimization": reducing the parts count by clipping out parts until the circuit stops functioning, putting back in the last part removed, and calling the design complete.

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Well that can result in a design, but likely not a good or robust design.