• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Voltage Clamping Circuit need help

Status
Not open for further replies.

panfilero

Member
I need to make a circuit that limits the voltage range in two direction, my range can't fall below 3.9V and can't go over 5.3V... does anyone know how I could make this? I've been thinking about using Zeners, but I see how that would be spiffy for one direction say a 3.9Vz but once I start going the other way I'd be limited by the Zener's forward voltage... around 0.7V... which is not good...

I need to be within 200mV of my target...

thank you
 

Tesla23

Member
I need to make a circuit that limits the voltage range in two direction, my range can't fall below 3.9V and can't go over 5.3V... does anyone know how I could make this? I've been thinking about using Zeners, but I see how that would be spiffy for one direction say a 3.9Vz but once I start going the other way I'd be limited by the Zener's forward voltage... around 0.7V... which is not good...

I need to be within 200mV of my target...

thank you
Lots of ways, one is to have two voltage rails at say 4.5V (= 3.9 + 0.6) and 4.7V (= 5.3 - 0.6), two diodes (assuming 600mV forward drop) and say a 4k7 resistor. You can refine it.
 

panfilero

Member
I'm sorry you lost me...

Are you saying something like... get two zeners, a 3.9 and a 5.3, put them in series with one another but pointing in opposite directions... and put that 2 zener combo in parallel with my load?

So in one direction it would be 3.9 + 0.6 and in the other direction it would be 5.3 + 0.6... basically Zener Fwd Drop + Zener Voltage in both directions...

Are Zeners ok to use in a fwd drop voltage limiting kinda way?

much thanks
 

eblc1388

Active Member
Zener voltage varies a lot and also depends on current. You are better off using a variable zener TL431 which enable you to trim the voltage easily.

I throw up the following circuit to see if it fits your requirement.

 

Attachments

MikeMl

Well-Known Member
Most Helpful Member
About the best you can do without using an op-amp. V3 has to regulate when back-fed, so R2 provides a minimum load on it. Clipping levels at both ends adjustable by varying V1 and V3.
 

Attachments

Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top