Switching between parts of a circuit with a pulse input

Hi,

I need some help in building a DC voltage multiplier.

This is the circuit I have so far (made this is PSPICE)
**broken link removed**

This is a 9V DC power source, to a 555 timer to get a square wave. Then fed through a Half-Wave Series Multiplier (Villard Cascade) to get a high voltage DC output.

Now, what I need help on is to have some sort of trigger switch device that will allow me to switch between the outputs of Vout2 and Vout3.

Ideally I want to be able to send a single pulse at 5V pulse from a micro-controller to the switch to change the resulting output of the system between those two points.

Something like.

Vout2-------o
...................\____Vout_system

Then pulse in changes it to
....................____Vout_system
.................../
Vout3-------o

(ignore, '.'s just used them to get the spacing)
Any help is welcome, improvements, part changes, design overhaul, switch part number, etc.
Thanks!

-Edit-
I think that I should include basically what I am trying to accomplish with this circuit as it seems that I may have chosen possibly the wrong path to pursue.

First off, I wish to be able to power the circuit off of a battery source, hence the 9VDC. What I wish to accomplish is to get a about 30-40V square wave output.
I was going to add another 555 timer at the end of the diagram that I originally posted to get the square wave. So I guess it's kind of a circuitous route to take, DC-->AC-->DC-->AC, lol.

Thanks!

Firstly, it is easier to have a level from a microcontroller so that high = one voltage and low = the other voltage. I don't know if that is what you intended.

Secondly, you could lower your component count a lot by using a boost converter. You can easily get a microcontroller to change the output voltage of a boost converter. I assume that you want two possible fixed output voltages, and a boost converter would be good for that.

If you want to stay close to your design use a toggle switch made with a CD4027.

The outputs change state with each high pulse edge on the input, which has to go low before next triggering.

Boncuk

Hi guys,

Thanks for the extremely fast responses.

To Diver300:
I took your advice and looked into the operations of a boost converter. However, I feel so lost in understanding how it works.
Is it that when the switch is closed, that the inductor is storing energy and when it is open that the energy is then released?
Any recommendations on what type of switch to use?
Does the boost converter function by pulse-width modulation?

To Boncuk:
Is this the chip you are talking about?
https://www.electro-tech-online.com/custompdfs/2008/11/fn3302.pdf
It looks like 2 flip-flop switches on a single chip.
How would I be able to make a toggle switch with the chip?
Do you mean something like a master-slave (pulse-triggered) D flip-flop?
Also, would the input pulse have to be constant high to keep one route and then constant low to keep the other route?

Thanks guys!

I think that I should include basically what I am trying to accomplish with this circuit as it seems that I have chosen possibly the wrong path to pursue.

First off, I wish to be able to power the circuit off of a battery source, hence the 9VDC. What I wish to accomplish is to get a about 30-40V square wave output.
I was going to add another 555 timer at the end of the diagram that I originally posted to get the square wave. So I guess it's kind of a circuitous route to take, DC-->AC-->DC-->AC, lol.

Hi guys,

Thanks for all your help. Im going to go with a boost converter instead with a MOSFET as the switch. All I have to do now is specify which diode and inductor to use. Any thought?
I will have an input of either 9, 18, or 4.8V, and will need any output of around 30V. This will be determined by pulse width modulation, correct?

How much current are you hoping it will supply? What's it for?

I am trying to limit the current draw. This circuit will be part of a larger device, but essentially it will be to output a square wave to muscle stimulating electrodes. Hence the desired low current. I would like to limit it to under 100mA as to not cause skin irritation.

Thanks!

TheRabbit2 said:

To Boncuk:

Is this the chip you are talking about?
https://www.electro-tech-online.com/custompdfs/2008/12/fn3302.pdf
It looks like 2 flip-flop switches on a single chip.
How would I be able to make a toggle switch with the chip?
Do you mean something like a master-slave (pulse-triggered) D flip-flop?
Also, would the input pulse have to be constant high to keep one route and then constant low to keep the other route?

Click to expand...

The switch toggles Q14 and Q15 every time the switch is depressed. The duration of switch activation has no influence on the function. However to toggle again the switch must be released for a short time. (to have the input return to ground) The first half of the IC produces a needle shaped pulse to trigger the second half.

Boncuk

Hi guys,

Again, thanks for all your help.
My electronics knowledge is very limited so only now have I understood how a transistor works. So now I have slight problem or misunderstanding.

Is it possible to use a MOSFET in the original circuit design I have above? Since a transistor only passes current and not voltage, correct? Also, how does a transistor negate the voltage potential?

Thanks!

If your not familiar with SMPS boost converter, your best bet for success is to use a low cost well established controller such as the MC34063.

For instance you could pick up a NCP3063 for fifty cents here


The NCP3063 is an enhanced version of the old MC34063 with a max switching freq of 150kHz using the internal switch and up to 250kHz with external switch. For your low power you don't need an external switch.

I don't know where you are but these are Canadian dollars.

Then you just go here


You can download an excel spread sheet that will calculate all external components. In your case all you will need is an inductor a Schottky diode and a few other passives.

Forgot to add you should be able to build this for about a buck.Just buy everything you need from one distributor to minimize shipping cost,and if your not in any particular hurry just use snail mail for delivery rather then a courier like UPS etc.

Hi,

Thanks for the link. It's helped me understand pulse width modulation more. I guess with this chip I won't have to go through setting up a mosfet inductor and a diode now.

I just wanted to make sure I am reading the specsheet correctly. It states that the input voltage is operation to 40V, but I cannot find the operational voltage. However it says that Vcc is 0 to 40V. So I am kind of confused there. But an input of 18V will be able to power it (2x 9V batteries), or 4.8V (4x AA batteries), correct.

In order to run the circuit, I will just have to set it up according to figure 19 in the specsheet correct? And depending on the pwm of the on off, I will be able to output basically any voltage? such as 36 to 100V? It looks like the output voltage is determined by the capacitor used.

One final question, how do I control the on off? I would like to interface this chip with a microcontroller to change the frequency and amplitude of the output pulse. Would I be able to replace the capacitor with a changing current output from the microcontroller? But then I am not sure how the frequency of the output could be changed. A 555 timer?

Thanks!

hai, i used cd 4027 ic to toggle the relay for automatic switchng on & off of my bathroom. but every time i should reset the IC. plz help me

also i wanted to ask you that can i use 10 volts input current for IC???
because 9V relay is not available so i am using 12 volts relay.

You should be able to use 12V with the cd4027, it says that the input range is from 3 to 15V.

Also, what are you using the switch for in the bathroom? If you are just using it for on and off, you should be able to just be able to use half of the cd4027 chip (a single JK flip-flop).

The specsheet is here:http://www.datasheetcatalog.org/datasheets/134/206735_DS.pdf

hey rabbit.... i just wanted to ask you that if u have built that flip flop circuit can u please send me that circuit diagram...
its very important for me plzzzzzz....