Zen I/V Converter

[juma]

Originally Posted by bogdan_borko

You missed 10K/4n7 on output , they are the load too!

4n7 makes a LP filter together with drain resistors (1k). 10k is not functional part of the circuit. It just represents the possible Zin of the next stage.

[Melon Head]

OK just to keep you happy.
Here is results of ZEN IV with 10k resistor and 4.7nF.

[Melon Head]

OK let see what the elephant on the dance floor is doing.

Need I say this design kicks **** (Thats *** for my American friends)

[Melon Head]

Well the Zen IV could also be classified as an opamp. I was referring to IC opamps.

I have done simulations if you are interested
see here
Zen I/V Converter

[Melon Head]

Balanced Zen IV

FFT of 4Vpk into 50k load

[Melon Head]

That balanced fft is a mistake.
The correct balanced fft is below.

[Melon Head]

OK when are the pcbs available for purchase.
I will definitely be purchasing.

[masag1]

Originally Posted by juma

How about using 0.1uF instead of bulky 10uF? It's possible if the ZEN I/V is loaded by B1 running at approx. +/-10V (it's easy to scale down from +/-30V). Additional benefit is higher drive capability.

That is a quite good idea, juma!

I have a hypno board left (wise idea to buy some more).

How shall I do the down scaling? Just change the resistors for the same current as with 30V?

Greetings

Sam

[juma]

Originally Posted by masag1

...How shall I do the down scaling? ...

RC combo is the easiest way to do it (like R1/C1 or R2/C2 in ZEN I/V schematic). For example:
I make my buffers with BF862 running at 10mA. We want to loose 20V. So, we'll need 2k resistors rated at 0.5W at least. C member can be usual 220uF or less.

R2 sets the DC offset, buffer's Zout is approx. 50R. Schematic would look like this:

[rsdio]

Originally Posted by regal

Problem with this is you would be stuck with balanced ouput and the input would require 2 extra DACs. R2R DAC chips aren't chip or easy to find these days.

I do not understand why extra DACs would be needed (did you mean 2 total, or 2 extra? 3?).

Current-output DAC chips often have two outputs; each is a complement of the other. When the sample bits are loaded for conversion, each bit switches a fixed current to one or the other output, and thus the total current through the chip remains constant - and that's much better than having the total current load on the supply change frequently.

In other words, with a complementary current-output DAC, only one chip is needed.