SSR03 configuration

[TheShaman]

Hey all,

I'm in the process of ordering parts for (one of) my SSR03 board(s) and had a couple of queries.
Target voltage is +/- 18V and the load will be a digital (DSP) board.
I already have the LM431 & LM329 18V Excel files/BOMs but was wondering if it makes sense to go for a lower noise LT1028-based setup, given the specific application. Any other BOM changes that'd have to be introduced other than the opamp itself?
Regarding the reference, what are the difference between 431 and 329? Do they offer identical performance?

Thanks in advance! :)

Happy holidays!

[peranders]

You can just change to LT1028 or LT1115.

The LM329 has better stability but worse precision. In your case is it either type.

[TheShaman]

Thanks P-A!

Unfortunately Mouser does not stock either of the LT devices, but I think I've located a couple of eBay sellers that look legit (Germany-based).
If I don't find a good excuse to place an order with Farnell as well, I'll try my luck with those.

[peranders]

I have LT1028 in my webshop if you are interested.

http://sjostromaudio.net/shop/semiconductors/54-lt1028.html

[TheShaman]

Thanks, hadn't spotted that!
If I manage to avoid placing a Farnell order, I'll grab a couple from your store.

[TheShaman]

Just got around to building this baby - better late than never.  :mrgreen:

Sorry for silly question, but can you please confirm that the dot (see green arrow) is there to show proper DIP opamp orientation?

By the way, I'm going to use sockets for the LT1028s; hope that's OK.
I know some people fret about the use of these things and prefer direct soldering, but sockets make troubleshooting so much easier..   :-)


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[peranders]

The dot is pin 1, correct.

Sockets will increase the pin length = increase the inductance. This is bad for fast opamps. I never use sockets in real applications but for testing purposes it can be practical.

[TheShaman]

Soldering done.  Went smoothly.  :-)

I'm about to use temporary sense jumpers (to test everything is OK), but for the final application I'd rather use the sense connections.
Does that mean that, other than removing the jumpers, I will have to install R51, R52, R53, R54 and C61, C62, C63, C64 as well?
Forgot to order those, but I may have something in my parts bin.

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[peranders]

Just put a tin blob on J1-J4 when you test.

[TheShaman]

It lives!

Using an 18V transformer, as Selectronic's R-Cores typically have higher-than-rated output voltage.
This one outputs 24V AC unloaded and 23V AC with SSR03 connected; I get 18,05/-18,07 at SSR03's output .
I'll hook it up on the oscilloscope and also try it on the actual load tomorrow.

If I want to use the sense connections do I just undo the jumpers or do I have to populate R51-R54 and C61-64 as well?

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