BBD tester

[Tony Forestiere]

Sweet deal Larry...

Now maybe you could sell these to some of those Chinese fellas on eBay! 

Wondrously witty. Good job! 

[armdnrdy]

Sweet deal Larry...

Now maybe you could sell these to some of those Chinese fellas on eBay! 

This is a weapon to be used against some of those sellers on ebay! 

[armdnrdy]

Here is a short video of the tester in action with a MN3204:

I designed this tester to be very user friendly.
If you can operate a toaster....you can operate this tester!
You insert a BBD into the Ziff socket, turn the power on, press the start button, read the display. That's it!

[fendman]

I have been following your project Larry, hats off to you..this is great work.

Love  the video.

Mike

[armdnrdy]

Thanks Mike.

I have a few things left to do before I commit to the main board.

The total current draw when the display is reset to all zeros is 350ma. This means that I need a bigger heat sink for the voltage regulator.

With the enclosure being fully enclosed, the chance of heat building up is very high.
I am working on taking the power supply components (regulator, filter caps, and wire pads) off of the switch board and building a small board which would mount to the inside back of the enclosure.

This way....I could mount a larger extruded aluminum heat sink (or multiple smaller heat sinks on a section of aluminum stock) on the outside back of the enclosure.
I plan to mount the regulator to the heat sink through a cut out in the rear of the enclosure, covered by the heat sink.

It should work out okay!

[fendman]

Hi Larry I am sure it will all work out  I have  a question for you, which I hope is not too stupid.  But with your help it might give me a better understanding of this part of the circuit which is  the Bias Voltage Display.
When you start to test BBD's with Neg bias as in the MN3007 etc... How do you get around making the LM3914  pin4 Rlo
and pin 6 Rhi threshold voltages negative?? The IC seems to only cater for Positive volts.

Does that make sense.. Or have I missed something very obvious?


Thanks
Mike

[armdnrdy]

Hey Mike,

Good question.

It is a rare occasion when a design feeds a "negative" voltage BBD with actual negative voltage.

Let me explain.....The MN30XX series BBD is designed to feed the VDD pin with a voltage that is "more" negative than the ground pin.

Since most designs using BBDs don't incorporate a bipolar voltage, the ground pin is fed with the positive supply and the VDD pin is connected to ground. The VDD pin is now more negative than the ground pin.
The IC doesn't know the difference.

[fendman]

Larry you made that sound easy... I should have known, after building a few designs that have bbd ic's .

....anyway thanks for the explanation appreciated. Can't wait to see this project come to fruition

Thanks
Mike

[armdnrdy]

I worked out the switch/clock main board. Removed the power components and moved things around a bit.



It's a little neater than the bread board. 

[armdnrdy]

Here is the display board. You can see why I chose to construct the board rather than bread board it.

This board consists of four 7 segment driver/counter ICs (CD40110BE), and the LM3914 dot/bar display driver circuit for the visual bias indication.

[fendman]

 Yes, you wouldn't want to breadboard all that

The boards look first class Larry,will be a joy to put components on them.

Nice work.

Mike

[armdnrdy]

Thanks Mike.

I worked up a drilling template/enclosure artwork mock up:



I have to etch and drill the main board when I get some time.....and make the power regulator/filtering board.

After working on this thing on and off for a year and a half....it nice to see that it's getting close!

[fendman]

Looking good Larry, what size/kind of enclosure do you have in mind... sounds though it might be fairly large being its 3 boards.

Mike

[armdnrdy]

Hey Mike,

I designed the boards around a Serpac 07-S-Black enclosure.

http://www.serpac.com/07s.aspx

It's the sloped enclosure that I show in the video.

The enclosure has screw point "stand offs" on the underside of the top and on the bottom cover making the two "stacked" boards easier to manage.

The third Ziff socket board is being attached directly onto the underside of the enclosure top.

It will make more sense when you see it finished. 

[fendman]

Hey Larry, that will be an expensive enclosure in the UK. There is a Serpac UK subsiduary company.  I was just looking at their postage

prices...anything under £100 is £10   So i didn't ask for a quotation    Would have to look at something close to those measurments from other 

sources.

Thats life.. you guys in the Apple are really lucky with component prices

Mike

[armdnrdy]

Hey Mike,

Here is a link for Digi-Key. Check out their shipping cost to where you live....see if it's any better.

http://www.digikey.co.uk/product-detail/en/07S,BK/SR07SB-ND/123361

I often look through a suppliers goods to see if there are other things that they have that other suppliers don't stock.

That way it offsets the shipping cost for the one specialized item that I need from them.

[scratch]

Larry, would you mind posting the full schematic showing the SAD1024 part? I don't mind bread-boarding this thing. I only have a pair of SAD1024's and SAD4096's to test.

I bread boarded an 8-digit audio frequency counter once, so not a real issue for me.

thanks.

[Scruffie]

Hey Larry, that will be an expensive enclosure in the UK. There is a Serpac UK subsiduary company.  I was just looking at their postage

prices...anything under £100 is £10   So i didn't ask for a quotation    Would have to look at something close to those measurments from other 

sources.

Thats life.. you guys in the Apple are really lucky with component prices

Mike

The console instrument enclosure here would probably do? http://www.bitsbox.co.uk/boxes.php

[armdnrdy]

WoW!!

I can't believe that there is a little bit of interest in this thing!

You guys understand that THIS IS NOT A FUZZ BOX!......Right?
And you cannot plug your guitar into it! Right? Okay then....let's proceed. 

Scratch,

I don't have the SAD separated from the other BBDs. This is the whole zif socket board circuit:




Scruffy,

This console?



If this is the one....it should work fine.

I've had to put finishing the first tester (positive voltage) on hold for a bit while waiting on an extruded heat sink from China.
I checked the tracking earlier.....the heat sink has landed in Los Angeles!

There are other ways I could have accomplished the heat sink....but I just liked the look of one long heat sink across the back.

In the meantime, I worked up a few attachment boards to work with the negative voltage BBD tester for less common ICs.

One will only test the MN3011....all six outputs with a rotary switch.
The other board will test MN3001, 2, 4, and 10. One slide switch to choose between pin 7 being connected to V+ or N/C.

[scratch]

Thanks Larry!!!