Eye Movement Desensitization Rehabilitation device

[KrisBlueNZ]

Kind of. A regulator contains an op-amp. But they're not really interchangeable.

 

[CommanderLake]

How about this with a 2 way pot and emitter followers on the output: circuit

I wont get full output but it reduces the part count and the heat is divided between 2 transistors.

 

[KrisBlueNZ]

I wouldn't do it that way. You don't gain much over using a silicon PNP emitter follower. One less transistor, splitting the heat in two, but at the cost of a dual-gang potentiometer.

I wouldn't be too obsessed about the heat issue. I only mentioned it to point out one way that a simulator won't tell you everything you need to know. A fairly small heatsink will deal with the heating, and even that may not be needed. That said, that circuit will work, with reduced output voltage as you say, if you fix the error - the non-inverting ("+") input of the second op-amp should be connected to the non-inverting ("+") input of the first op-amp, not to the output of the second op-amp.

 

[CommanderLake]

Thanks and FYI by checking "show power" in the options menu, components consuming power and therefore generating heat will glow red this can be tuned with the power brightness slider on the right.

You make it sound as if double pots are expensive?

 

[KrisBlueNZ]

Cost doesn't just mean expense. But really, it's your project; you do it however you want.

 

[CommanderLake]

How would I connect up a double pot on strip board?

 

[KrisBlueNZ]

Erm... with solder?

Here are two options available from Farnell:

BI Technologies P140: http://uk.farnell.com/bi-technologi...f25br10k/pot-rotary-10kohm-20-50mw/dp/1417134
This is the cheapest option. It has six pins in a line, spaced at 2 mm pitch. This doesn't fit stripboard (2.54 mm pitch) but you can probably bend the pins to fit.

TE Connectivity 27ESA: http://uk.farnell.com/te-connectivity-citec/27esa103mmf50nf/potentiometer-d-gang-lin-10k/dp/1173890
This has two rows of three terminals. Each terminal is a solder lug. You would use insulated wires from the potentiometer to the stripboard.

Farnell have a few other options. The pictures and descriptions don't all match properly though. I'm sure you can figure it out.

 

[CommanderLake]

I meant if it were through hole with a stacked pot they would share strips which would make it tricky hooking up the one closer to the edge of the board, solder lugs may be the better option.

10k is far too high it makes the intensity control logarithmic I wouldn't go higher than 5k even that makes it slightly logarithmic.

 

[KrisBlueNZ]

It's not too difficult to cut a strip between two adjacent holes. Use a sharp blade like a scalpel and cut a V-shaped channel, about 0.25~0.5 mm wide at the top, in the board across the width of the strip.

 

[CommanderLake]

I give up your way is better, single emitter follower it is.

 

[CommanderLake]

What sort of wire do I use to connect different locations on strip board?

Ah I believe its insulated wire with a solid conductor I need

 

[(*steve*)]

What sort of wire do I use to connect different locations on strip board?

Ah I believe its insulated wire with a solid conductor I need

Depending how long the wire needs to be and whether it goes near any other component, bare wire can be used (we're talkilng veroboard, right?). If the jumper isn't flat against the board, just jumpering to a hole a couple of rows away, insulated may be better.

 

[CommanderLake]

Is there a program that can help find the most efficient layout of components on stripboard(veroboard is brand specific)?

 

[(*steve*)]

Is there a program that can help find the most efficient layout of components on stripboard(veroboard is brand specific)?

There are programs that will help you lay the board out, but nothing (that I'm aware of) that will optimise it. Optimization is a very tricky task, and there are many things you might want to optimise for.

It's a bit like auto-routing of PCB tracks, except that so few people use veroboard commercially that there's not much money in it.

 

[CommanderLake]

A basic program to visualize the layout will do, any suggestions?

 

[(*steve*)]

http://www.abacom-online.de/uk/html/lochmaster.html
http://www.windows8downloads.com/win8-veecad-snlzghzt/
http://www.electroschematics.com/2270/veroboard-design-software/
http://veecad.com/

A few google hits

 

[CommanderLake]

I got those results too i was just chicking if anyone had any preferences.

 

[CommanderLake]

I made a working prototype on a breadboard and it works great!

The voltage across the emitter follower is just 0.55v.

 

[KrisBlueNZ]

Good one!