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

[audioguru]

I agree that only one voltage regulated is needed.
The 740 thousand uF capacitor is impossibly enormous and should be only 470uF or 1000uF.
You show wrong pins on the BD139 transistor.

 

[gary350]

I found a 10v 10a transformer in my stash. Here is the new circuit. I read voltage drop across a 78xx regulator should not be more than 3v.

 

[crutschow]

Why do you even need a 12V regulator?
The 555 frequency and duty-cycle are relatively insensitive to supply voltage.

 

[ronsimpson]

The NE555 is good to 15V. That is close to 14.2V unregulated. How good is your power line? I would stay with the regulator.

78xx regulator should not be more than 3v

Should not be less than 3V.
Here is a curve of output current and Vin-Vout. You are nowhere close to 1.5A so that is good news. And with out the transformer current the current is very low. Note this is at 25C. I say the "3V" comment is for full current. At your power levels you should keep 2V, or more, across the part.

 

[gary350]

Why do you even need a 12V regulator?
The 555 frequency and duty-cycle are relatively insensitive to supply voltage.

Because 555 is 14 volt. There is a certain 555 number that is 18v but all mine are 14v. I have smoked some at 14.5v. I smoked 1 on 14v

 

[shortbus=]

Won't tying the HV coil ground to the 555 circuit cause spikes in the low voltage circuit too?

See this circuit - https://www.rmcybernetics.com/science/diy-devices/diy-ignition-coil-driver He has been around along time doing this. He even sells his circuits instead of just posting unverified circuits to the web.

 

[chemelec]

This Fencer Works Good.

 

[crutschow]

There is a certain 555 number that is 18v but all mine are 14v.

Okay.
Didn't know there were some with such a low rated maximum voltage.

 

[gary350]

New circuit. Since the TV HV transformer is designed for RF and ignition coil is designed for 1 sparks I decided to use the ignition coil in this circuit. I also decided to use 2N3055 power transistor this will give more current to the ignition coil. Someone suggested a 150 ohm resistor connected to transistor base so I will try that first then compare that to 100 ohms to learn what different is makes. I changes variable resistor to fixed resistors for 2 second plus as someone suggested. The 1N4007 diode on the transistor appears to be a short circuit from C to B. I wish I had a selector switch for R1 & R2 so I can flip switch for 1 second pulses to 2 second pulses.

 

[ronsimpson]

The Base-Emitter voltage of a 2N3055 is small. Around 0.7V. That will not turn on the LED.

The LED needs to get its current through a resistor directly from the NE555 pin3.
OR
Put the LED in series with the 100 ohm base resistor, If the LED can take that much current.

 

[audioguru]

1) The LED connected to the base of the transistor will never produce any light, because the base-emitter turned on voltage will be only 1V.
2) The 100 ohms base resistor has 9V across it (if you have an original 555) which is a current of 90mA. With this fairly low base current the 2N3055 saturates with an output current of only 900mA.
3) The 100nF capacitor with your resistor values produces very short duration pulses and pauses. 8us and 200us.
4) The timing resistors are backwards producing 200us output current and 8us pauses between output current.
5) The datasheet for the LM555 shows 20uF with a 10k resistor for a 0.1 second pulse and about 330uF with 280k for 1 second pauses.

You talk about "555" ICs but you do not say if they are the original powerful NE555, LM555 or the weak Cmos LMC555, TLC555 and ICM7555.

 

[gary350]

1) The LED connected to the base of the transistor will never produce any light, because the base-emitter turned on voltage will be only 1V.
2) The 100 ohms base resistor has 9V across it (if you have an original 555) which is a current of 90mA. With this fairly low base current the 2N3055 saturates with an output current of only 900mA.
3) The 100nF capacitor with your resistor values produces very short duration pulses and pauses. 8us and 200us.
4) The timing resistors are backwards producing 200us output current and 8us pauses between output current.
5) The datasheet for the LM555 shows 20uF with a 10k resistor for a 0.1 second pulse and about 330uF with 280k for 1 second pauses.

You talk about "555" ICs but you do not say if they are the original powerful NE555, LM555 or the weak Cmos LMC555, TLC555 and ICM7555.

1. Your right. I copied that from another circuit. It looked good but now I see it will do nothing.

2. I don't know how to do circuit math I have no clue what your telling me to do?

3. Someone else said that is correct for 2 seconds I took there word for it.

4. I copied that from TTL book. 555 online calculator says 50 and 950 ohms for 1 second pulses.

5. OK

I have NE555P and LMA555CN I have cooked some of these at 14v and 14.5v that is why I want to use 12v. If I had an 18v 555 that would be great.

I need to go back to what i know, read the TTL book for correct values, do math see what I get.

 

[crutschow]

The 1N4007 diode on the transistor appears to be a short circuit from C to B.

That diode does nothing in your circuit.
If it's to protect the transistor, it needs to be a Zener with voltage about 20% below the transistor rating.

I wish I had a selector switch for R1 & R2 so I can flip switch for 1 second pulses to 2 second pulses.

You can add a switch that will add a 274K resistor in parallel with R1.

But reverse the diodes as AG noted, and change the cap from 100nF to 10uF.

about 330uF with 280k for 1 second pauses

That gives a time-constant of 92 seconds, which is not correct.

 

[ronsimpson]

The 1N4007 diode on the transistor appears to be a short circuit from C to B.

That diode does nothing in your circuit.

The diode from C-E on the 2N3055 is to prevent the Collector voltage from going negative. (fly back diode) Common in the horizontal section of TV sets.

 

[audioguru]

That gives a time-constant of 92 seconds, which is not correct.

Sorry, i goofed and I should have copied then marked the graph.
The diodes affect the timing a little.

 

[Nigel Goodwin]

New circuit. Since the TV HV transformer is designed for RF

Except it's not, why would you imagine it was?.

Chemelec has posted an excellent example of how to make an electric fence, why not just build his well designed, tried and tested circuit, instead of your usual random collection of components connected in random ways?.

 

[audioguru]

If your hearing is normal then you can hear the 15,625Hz (European) or 15,750Hz (US frequency) switching of the TV HV transformer.
The max frequency of a car ignition transformer is 12 cylinders x 8k RPM= (12 x 8k)/60= 1.6kHz. A 4 cylinders 5k RPM car produces 333Hz.

 

[eTech]

Hello

I readjusted the timing components to obtain 100ms on for 1 second and 2 second intervals

eT

 

[gary350]

NE555P is 16v according to 2 different datasheets. Another datasheet says 15v max.

I can find nothing on LMA555CN

Years ago i killed some 555s with 9 batteries in series that should = 13.5v but its not. I was testing new batteries yesterday digital meter shows them to be 1.65v each, 9 batteries = 14.85v. Not all batteries are the same I have some new rechargeable batteries that are 1.4v and I learn battery by different company are different voltage too. But they are all called 1.5v battery.

My 10v transformer will be 14.14v after the bridge rectifier and filter capacitor. Maybe I don't need the 7812 if I use the NE555P

I made a mistake on the 18v 555 I was looking at LM386 data newer version.

I have no information on this circuit with the 100k variable resistor? What does the adjustment do?

 

[eTech]

NE555P is 16v according to 2 different datasheets. Another datasheet says 15v max.

I can find nothing on LMA555CN

Years ago i killed some 555s with 9 batteries in series that should = 13.5v but its not. I was testing new batteries yesterday digital meter shows them to be 1.65v each, 9 batteries = 14.85v. Not all batteries are the same I have some new rechargeable batteries that are 1.4v and I learn battery by different company are different voltage too. But they are all called 1.5v battery.

My 10v transformer will be 14.14v after the bridge rectifier and filter capacitor.I Maybe I don't need the 7812 if I use the NE555P

I made a mistake on the 18v 555 I was looking at LM386 data newer version.

I have no information on this circuit with the 100k variable resistor?

**broken link removed**

You'll need at least 11.6VAC output from the XFMR:

12V Out + 3V D.O. + 1.5V Br. Rct = 16.5 Pk = 11.6 VRMS = choose 120VAC-14VAC

eT