555 Timer Circuit(s)

[Joit]

Hi.
First of all, Many Thanks to Paul Falstad and his Circuit applet.
He does have other many interesting Applets there also.
Math, Physics, and Engineering Applets

I did play around with it, and it becomes handy for me.
Its an usefull Applet where you see how Current runs and what do happen in there and it works so far i can see.
I build up a Timer Circuit, what runs from 500hz up to 4khz,
I can still adjust to a low duty cycle and frequency, even when it is some tuning around at some cases.
A Meter for measure the Frequency is very handy for that, or an Oscilloscope for the Duty Cycle.

First download the Zip File from here,
http://www.falstad.com/circuit/circuit.zip it (fast, fast, so far it is still free, lol), is not very big.
Extract the Zip file into a new Folder with a Name of your Choice.
Make sure, you have Java installed, else download it from here. java.com: Java + You

Double click at Circuit.jar at this new Folder, and the Applet with a standard Circuit comes up.
Click right top at the Menu at File-Import. A Empty Box comes up, and past this Digits in.

$ 1 1.0E-6 2.803162489452614 50 9.0 43
165 496 128 688 128 2 0.0
v 112 272 112 208 0 0 40.0 9.0 0.0 0.0 0.5
c 256 352 256 416 0 1.0000000000000001E-7 3.010186976662886
w 112 272 112 416 0
w 112 416 256 416 0
g 112 416 112 448 0
w 112 96 112 208 0
p 640 192 688 192 1
174 224 128 256 192 0 50000.0 0.33170000000000005 Resistance
w 224 96 112 96 0
d 624 320 624 352 1 0.805904783
w 224 96 224 128 2
w 496 96 560 96 0
w 560 96 624 96 0
w 464 160 496 160 2
w 624 192 640 192 0
w 640 192 640 320 0
w 640 320 624 320 0
w 624 352 528 352 2
w 496 368 432 368 0
w 432 368 432 352 0
w 432 320 432 192 2
174 432 128 464 192 0 10000.0 0.18320000000000003 Resistance
174 496 336 528 368 0 10000.0 0.9554000000000001 Resistance
w 432 352 432 320 0
w 496 192 432 192 2
w 400 192 432 192 0
w 624 160 624 96 0
w 400 192 256 192 0
w 256 96 496 96 0
w 256 160 256 192 0
w 224 96 256 96 0
w 496 256 496 224 0
w 496 224 496 192 0
w 256 272 256 352 0
w 256 192 256 272 0
o 7 64 0 363 18.707220957835556 9.765625E-55 0 -1
o 7 16 0 42 10.0 1.52587890625E-6 1 -1
o 2 64 0 35 10.0 0.025 2 -1

Now you can see the Circuit and how it runs, when you change one of the 3 Resistors right Side below.
Optional you can place another 1K 5k or 10K Potentiometer to R1 Left Side top in Series, for a better fine Tuning.
Right side Top are Levers for the Simulation Speed.

Some other Keys for the Applet.
Mouseover an Object and holding Ctrl + Shift + by pressing left Mousebutton you can move the Object with the Mouse.
Mouseover an Object and holding Shift + by pressing the left Mousbutton you can move the alignment from the Object.
Rightclick on a Object for a additional Menu like Show Voltage at the Object.
Richtclick on the Backround for additional Elements,
check them with your Mousebutton, go back to the Window and 'drag' them in with your Mouse
by pressing left Mousebutton and moving the Pointer.
Works for the Wires also.
Menu at Top File - Export, export the Digits over copy/past into a new Textfile anywhere on your PC,
to save your Work.
And please note the Circuits Examples at the Menu at Top.

Material needed.
R1 50k Potentiometer
R2 10k Potentiometer.
R3 10k Potentiometer.
Unpoled Capacitor 100nf or equal.
Optional 1k, 5k or 10k in Serie with R1(50K).
And dont forget to connect Pin1 with Ground and the one Side of the Capacitor,
which is assumed at the Applet.

Have Fun.

Circuit Simulator Applet
Circuit Applet done

If someone can make improvements, feel free to do so.

[Joit]

Additional Informations at the NE555 Timer Chip.
555 Timer Tutorials

Internal Schematic
The 555 timer
With the descriptions of the Pins.

When the reference Voltage (Pin8) at the Comparator(s) (Threshold Pin6+Trigger Pin2) is higher then 2/3,
the Flipflop switch the Output (Pin3) to low,
triggers Pin7, and discharge the Circuit over a Transitor connected to ground, until Vref is below 1/3.
If the Voltage is at 1/3 at Pin2, the Flipflop sets the output to high, Vcc will be leaded over a Transistor to the Output (Pin3).
The Flipflop switch to high, the Circuit charges up again till 2/3 Vref.

My output on Pin 3 was with a 9V Block at about 6,3 V, (at 300mA?)
so maybe another 2-3K Resistor or Potentiometer at the Base, when you run a Transistor at the Output, is may not a bad Idea

[Joit]

In case, when someone works with Spikes at the Input from the Timer Circuit,
it will help to prevent to damage the chip
when you place an poled Capacitor there between Plus and Minus, depends on the Size of the Spikes.

[Bizzy]

just thinking out loud

Good afternoon
I have been enjoying this thread and while reading it a question popped into my head you may beable to answer

I know that a 555 timer is for oscilating but could a 555 timer circuit be used to turn current on and off into a pulse motor?
And if so what would the circuit look like.
thanks
Bizzy

[Joit]

Hi
Of course, the 555 Timer has an output Pin 3, where you connect any Transistor at the Base over a Resistor.
The Transistor turns the Motor on an off.
The advantage from the 555, you can adjust the Frequency and the Duty Cycle during operation. The 555 Timer can handle 5-16V for itself, for the Motor you can take any Source what the Transistor can handle.
But only for a Pulse Motor you can make an easier Circuit as with a 555 Timer, when it only have to run at a certain Speed, or even only need to be adjusted at the speed.

I actually made this Thread for Circuits for the 555 Timer, because to find a good working one is seems still a Problem.
You may can find more Circuits at the Net for a Pulse Motor when you look for ' pulse motor control Circuit '.
Since a Pulse Motor has more Phases, you may need to use few Timer Chips,
where one triggers the other, because each Chip has only 1 Output.

[Joit]

This is how the Circuits do like like at the Falstadt simulator.

[Bizzy]

555

Good morning
I have been reading many of the 555 circuit tutorials but am still a little confused, could someone descibe the purpose of the various pins on a 555 chip so an untrained neophite like myself could undertsnad it.
Much thanks
Bizzy

[Joit]

Ok. A short Description from the Pins.
Even when the Description is allready at the inernal Schematic Link above.
The Chip itself works between a lower 1/3 Threshold and a higher 2/3 Threshold, which is oriented at the Supply Voltage.
IE. Supply Voltage is 9V, the upper Threshold is (2/3) 6 Volt, the lower Threshold (1/3) is 3 Voltage.
When the Voltage at Pin 2 reaches 1/3 from the Supply Voltage, the internal Transistor for Pin 3 turns on and makes a direct Connection between Supply Input (Pin8) to Pin 3.
When the Voltage at Pin 6 reaches 2/3 from the Supply Voltage, the Flop Flop resets, the Transistor for Pin3 (Output) turns off, until the Capacitor from the external Circuit decharges again to the low Threshold.
With reseting the Flip Flop, Pin 7 opens another Connection to Ground, what can be used to discharge the Capacitor and the Circuit again to the lower Threshold.
The 'Heart' from the Circuit is there the Capacitor, what charges up and down between 1/3 and 2/3 from Supply Voltage and turn Pin 3 Output on and off. Controlled by Pin2 and Pin6.

Pin 1 Ground.
Pin 2 Trigger (acts at 1/3 from Source Voltage)
Pin 3 Output (A direct Connection between Input Source Plus and Pin3, what is switched by a Transistor to on and off.
Pin 4 Reset (A Reset Pin, what switch the Output at Pin3 to low. If unused, it shall be connected to Plus Source (Pin8)).
Pin 5 Control Voltage. An Input Pin, what affects the Value from the 2/3 Threshold. Can used, to make the Threshold higher or lower.
Pin 6 Threshold (acts at 2/3 from Supply Voltage.
Pin 7 Discharge (A direct Connection to ground)
Pin 8 Supply Voltage Pin

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[Joit]

Ever seen a 555 Timer Circuit without mass in a Simulator?

Here it goes.
Simulator



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Well actually not really without mass, because the Simulation assumes a connection to Pin 1 from the Chip, which is Mass.

[boguslaw]

I don't know if this is the correct thread but I need information how to connect output of 555 to optocoupler and to mosfet to completly insulate switching side from low voltage side. I want to switch couple of amperes at 500V and this information is curcial for me especially if that would be big capacitor discharge and absulutely no radiant energy should go to the low voltage side. I worked in the past with 555 and low voltage mosfet with driving chip also but with optical isolation I'm not familiar yet. Could somebody help me ?

[Joit]

The 555 gives the same Output at Pin 3 what you feed it. The Chip operates at 5-15 Volts. Pin 3 is a direct connection between Input from the Chip and Pin 3 Output.
I would run the 555 Timer circuit then from a different Source, like a 9 Volt Block batterie or a second Power supply.
For the optocopler you need a Resistor, not sure what Value,
because i think its rated at 7 V.
For the Mosfet, i would use a potentiometer on base too, to regulate it back, when the Mosfet does open to much.

[boguslaw]

The 555 gives the same Output at Pin 3 what you feed it. The Chip operates at 5-15 Volts. Pin 3 is a direct connection between Input from the Chip and Pin 3 Output.
I would run the 555 Timer circuit then from a different Source, like a 9 Volt Block batterie or a second Power supply.
For the optocopler you need a Resistor, not sure what Value,
because i think its rated at 7 V.
For the Mosfet, i would use a potentiometer on base too, to regulate it back, when the Mosfet does open to much.

Joit

Thanks for help.What I never understood is how to make mosfet working like ordinary switch WITHOUT GROUND of low side driver connected to GROUND of HV side. Is that what optocoupler make possible ? Data-Source path controlled without biasing / connecting to gate ? I think there is a opto-transistor inside optocoupler which can make this bias but can it stand the situation when 2 or 4 mosfets are in parallel to pass 40amps at 400V ? I think some resistor may be required there also but I'm completly lost where to find any tutorial on using optocouplers ?

[citfta]

If you use the FOD 3120 or FOD 3180 chip you can drive up to 4 mosfets without any problem. This chip is made just for driving mosfets. It will make sure the mosfets are driven completely on and off. The ground connections for the 555 can be totally separate from the ground connections on the mosfet side. This will give you total separation between the high voltage side and the low voltage side. You can look up the data sheets for the FOD 3120 and 3180 to see the differences. I think the 3180 can take higher voltages, but look them up to be sure.

Carroll

PS: In post 732 of the 3 battery generating thread there is a schematic showing how to hook up 4 mosfets to one Fod 3180.

[boguslaw]

If you use the FOD 3120 or FOD 3180 chip you can drive up to 4 mosfets without any problem. This chip is made just for driving mosfets. It will make sure the mosfets are driven completely on and off. The ground connections for the 555 can be totally separate from the ground connections on the mosfet side. This will give you total separation between the high voltage side and the low voltage side. You can look up the data sheets for the FOD 3120 and 3180 to see the differences. I think the 3180 can take higher voltages, but look them up to be sure.

Carroll

PS: In post 732 of the 3 battery generating thread there is a schematic showing how to hook up 4 mosfets to one Fod 3180.

Thank you. Seems that chip is hardly available in my country, I have a few of simpler like 4N35 optocoupler

[Joit]

This one seems can keep the Freq stable when you change the Duty cylce and otherwise, works from 300hz-1,05 khz
Simulation




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