Baracuda Build (silverdog kit Rev2)

[Polymer]

@ Michaelo

Get well soon!

I have never ordered parts from China. I don't know if the parts can be trusted from there, because
I'm not sure if they may be reject batches with iffy specs finding their way back to the market instead of landing in the shredder ...

[Old cart]

Take the time to get well. No hurry!

[Chet]

An eye infection has delayed completing breadboard... (just in case anyone is watching this post)...
Mike

Hi Mike

That is a bummer; I hope it heels fast.

Have a good day,
Chet

[Michaelo]

An eye infection has delayed completing breadboard... (just in case anyone is watching this post)...
Mike

[Michaelo]

Mike did you ever finish your breadboard? If so what was the outcome?

The last two remaining parts arrived yesterday 1st June, they were due three weeks ago... talk about the slow boat to china...

The first breadboard (baracuda rev 3 test circuit) has all the other parts and connections so I only need to plug the remaining part in and start testing...
After that I will make the Bara-Micro breadboard and run some tests... I will of course report all my finding...

So give me a few days and I should have the test results...
Mike

[Old cart]

@Polymer...
I have a new baracuda board waiting for upgrade, just waiting for two components to finish the Rev 3 breadboard build...
After testing and assuming everything is working, I will make the necessary track changes and build the Rev 3 PCB and post all details...
Mike

Mike did you ever finish your breadboard? If so what was the outcome?

[Michaelo]

@Polymer...
I have a new baracuda board waiting for upgrade, just waiting for two components to finish the Rev 3 breadboard build...
After testing and assuming everything is working, I will make the necessary track changes and build the Rev 3 PCB and post all details...
Mike

[Polymer]

As I have already made so many changes to my current baracuda (not related to this post), I will need to purchase another bara and perform the upgrade on that.
This should allow testing of the new design and also allow me to provide the upgrade procedure for anyone who wishes to upgrade their existing Rev 2 boards...

Also, being able to upgrade from Rev 2 to Rev 3 should allow for current stock to be sold (basically negate the negative effect afforded by a new design) otherwise, outstanding tooling costs for Rev 1, would have top passed to the new board making it more expensive...

Mike

Hello Mike,

I am looking forward to the upgrade procedure, as I have two populated Baracuda boards ...

Much appreciating your efforts, Polymer

[Michaelo]

Just for testing replace the regs with 3 AA's and you can use a variety of common opamps for the 412

Might do if I can find some batteries... Have a bench power supply almost finished but again waiting for a transformer... I am always waiting on parts...

[6666]

Just for testing replace the regs with 3 AA's and you can use a variety of common opamps for the 412

[Michaelo]

Rev 3

Just waiting for a 3 components to complete breadboard build...

Are there any more changes?

[Michaelo]

Impulses's PCB (which I need to send back to him soon) has a 100k fitted. The board is working well with that value.

The input from the differential amplifier stage of the LF412 is coupled to the non-inverting, single pole active high-pass filter, by way of C17, R2 (high-pass)
As a rule of thumb, I think R28 should be the same as the feedback resistance (R29) which is 100K... otherwise, you can always calculate the cut-off frequency and substitute whatever value makes most sense...

Mike

PS, while searching google, I found two identical examples one labelled low-pass and one labelled high-pass... easy to make mistakes with op-amps...

[Qiaozhi]

Hi Q
the value of R28 (pin 5 of 2nd op amp) needs a question mark
as it changes from cct to cct.

Impulses's PCB (which I need to send back to him soon) has a 100k fitted. The board is working well with that value.

[6666]

Hi Q
the value of R28 (pin 5 of 2nd op amp) needs a question mark
as it changes from cct to cct.

[Qiaozhi]

Hi Q,

The existing board had a 4001 diode across the battery connections. I guess this is intended to help save the circuit on a reverse battery connection. I've seen it on another schema. How useful is it?

The threshold control is now 2M2 + 50K variable + 27K. It was 39K + 20K + 27K. So different, I'm wondering how it works out.

Ray

Sorry - I've only just noticed your post.
I have re-inserted the "protection" diode in the schematic. If anyone doesn't like it, then it's easy enough to just leave it out.
The 2M2 resistor is a mistake. It should be 39k, so I've changed that as well.

Haven't managed to breadboard the circuit yet, not enough space on available breadboard...
New breadboards (x5) expected tomorrow... will start immediately...
Mike

I'm a bit busy at the moment, but will get back to creating the new Baracuda layout soon.