how do I build a voltage limiter

[wenjokatee]

I don't know a lot about electronics. But I have a question about Multisim 8. There is a component called "voltage limiter" and I was wondering; does it have an assumed power source in the component in order to achieve the "gain" that that you can request in the parameter settings.

I need a simple explanation. For instance if I wanted to introduce 1v and wanted a gain of 100 v/v, does it need another powere source for that gain, and if not how could it be built?; simple version.

[LeilaFeyz]

Hi,

It does not have a power source and you can add your desired power source to it.When you add a Voltage_Limiter double click on it and go to info.There you can find a very simple example that shows how it uses a formula to calculate the output.

Regards,

Leila F.

Electronics Workbench Group
National Instruments

[wenjokatee]

Hi Leila,

Thank you for your reply.

Actually, that's the trouble. I can't view info because I have Windows Vista and the patch for that version doesn't seem to work from Windows. The question is; if it doesn't have an assumed power source, depending on your settings you choose for gain, how is it that it achieves the gain I have chosen for my circuit without me attaching an outside power source; only a signal source?

[LeilaFeyz]

Hi,

Yes from any source and Vout would be K(Vin+Voffset) if  Vmin<Vout<Vmax

else Vout=Vmax for Vout>Vmax

Vout=Vmin for Vout<Vmin

K is the gain that you set.

Regards,

Leila F.

Electronics Workbench Group
National Instruments

[wenjokatee]

Hello again, Leila

You seem to be telling me what I asked in my first message; that if I had a source voltage of 1v and I wanted a gain of 100v/v, and if the set parameters I put in allow it, that I could get 100 volts at the output with no other voltage introduced.

It seems as though you can't just go to radio shack and pick up this component. I've tried to locate one to find out a little more about it. And when you check online they only speak of it as a circuit that limits the output voltage as a control, but doesn't show that it also provides gain; even then there has to be a secondary voltage introduced as a control.

Help me if you can. Thanks

[JasonF · Accepted solution]

This control block is targetted as more of an idealized component. It was not based on a real orderable component, it is designed to simplify simulation of certain characteristics and allow for a more high level simulation which does not worry about the practical limitations of real components.

You can get very similar functionality from an OPAMP in a non inverting configuration. This would require an additional DC power source for the voltage rails and to produce the gain. The positive and negative rails would be your limiting values, and the amplifier gain would be equivalent to the gain generated by the control block. So they are functionally very similar, the only difference being the practical requirement of a second power supply.