Tisdale Buffer

[karbomusic]

Designed this week, thought I'd share.

- 1 input, 3 buffered outputs.

- 6 selectable input impedances.

- Phase/polarity invert switch for each output.

Sometimes I might want to purposely load the signal down some hence the reason I go so low on the impedance. Make them any value you wish; if you don't want it selectable, just install 1 resistor of choice and jumper it instead of using a switch. Work in progress but as of last night works great. Boxing up this weekend. My main use is for going to multiple amps and/or recording aka two mic'd amps + an additional clean signal going into the DAW. Input cap is oversized in the schematic because I was possibly going to use it for more than guitar so reduce accordingly if needed.







It's a double-sided layout. Since most here don't build those I didn't post a printable version but will do so if anyone is interested and wants one. Double-sided was much easier than I thought although it did take a little bit of thinking (and cheating  ).

[italianguy63]

Kary-- excuse my ignorance.  But what software are you using there for your schematics/PCB/CAD?

I'm using freeware-Eagle, and beginning to think I need a little "more.."

MC

[karbomusic]

Kary-- excuse my ignorance.  But what software are you using there for your schematics/PCB/CAD?

I'm using freeware-Eagle, and beginning to think I need a little "more.."

MC

No worries Mark... It's the freeware Eagle 7.2.

[italianguy63]

I'm using 6.5 I think... I want to be able to do those "ground-plane" type foils...

[karbomusic]

I'm using 6.5 I think... I want to be able to do those "ground-plane" type foils...

Should be able to do that in 6.5. Just create a polygon the size of the PCB then right-click > name > GND, click the rats nest button and voila. Just be sure to then right-click the polygon and set its isolation to something like .016 or .024 or whatever distance works best for you.

[italianguy63]

OK-- I will try when I get a chance.. I still do my traces pretty "angular"-- at like 45's... not rounded or miandering... yet.

I get by.  But, I would like to "fill" the unused space sometimes, and was wondering how it was done.  Your work looks stellar!

MC

[karbomusic]

Your work looks stellar!

MC

Much of that is owed to all of you guys so thanks!   

[mth5044]

I'm using 6.5 I think... I want to be able to do those "ground-plane" type foils...

Should be able to do that in 6.5. Just create a polygon the size of the PCB then right-click > name > GND, click the rats nest button and voila. Just be sure to then right-click the polygon and set its isolation to something like .016 or .024 or whatever distance works best for you.

Sometimes you have to use the name tool to change it as EAGLE may tell you there is already a path by that name.

Nicely done, though! That self etched double sided board looks awesome. How did you line up the sides?

[karbomusic]

Nicely done, though! That self etched double sided board looks awesome. How did you line up the sides?

I mirrored top/bottom with a little distance between them, then drew a vertical line at the "fold point":



Then after printing on PnP I carefully folded exactly on that vertical line but also held it up to a bright light to make sure the top and bottom holes were perfectly aligned. Used a wooden dowel to commit the fold, double checked alignment by holding up to the light then slid it over the double-sided PCB and tossed into a small t-shirt press. I can say I was very nervous when I drilled that first top hole to see if it actually hit the corresponding bottom hole. I also cheated some as there are no vias, I'll share that later. Maybe better stated that I shared the vias with the component holes.

[mth5044]

Nice idea!

Vias wouldn't make too much sense... You have to just solder in a tiny jump. Makes must more sense to use compnents as the conduit between two sides like you did.

[duck_arse]

karbo - nice work. if you hard wire the 10M impedance setter, and then switch the selected in parallel with it, you can SAVE yourself one wire to the switch, and your DC's won't lurch with each switch klik.

and if you print yourself a pair/quartet of targets outside the bounds of your board on your layout, when you fold you'll be able to align through paper/p'n'p instead of through copper clad (twice).

[karbomusic]

karbo - nice work. if you hard wire the 10M impedance setter, and then switch the selected in parallel with it, you can SAVE yourself one wire to the switch, and your DC's won't lurch with each switch klik.

Yep, I was lying in bed last night thinking of all the ways I could reduce it some including a few other tricks between parallel/series combos. Thanks for the idea.

and if you print yourself a pair/quartet of targets outside the bounds of your board on your layout, when you fold you'll be able to align through paper/p'n'p instead of through copper clad (twice).

Good point. I could also Pre drill four component holes in the existing PCB on one side and then use those holes to align the other side but I didn't do that here because I was able to do it in a single step with the t-shirt press, aka one heating for 90 seconds did both sides simultaneously (actually I flipped it but the first heating made the bottom stick enough to keep the registration). I literally slid it over the PCB and clamped it in the press without any alignment post fold.

If I can repeat this consistently I'll do it much more, the savings in PCB size is just too great to ignore.

[italianguy63]

I'm using 6.5 I think... I want to be able to do those "ground-plane" type foils...

Should be able to do that in 6.5. Just create a polygon the size of the PCB then right-click > name > GND, click the rats nest button and voila. Just be sure to then right-click the polygon and set its isolation to something like .016 or .024 or whatever distance works best for you.

I get an "invalid Polygon"...  Maybe we can PM

[karbomusic]

I get an "invalid Polygon"...  Maybe we can PM

By all means, PM as needed or I'll do you a video or something... you want to make it the size of the PCB with a final click to connect back to the starting point.

[karbomusic]

If this doesn't help, feel free to PM etc.

[wavley]

I'm using 6.5 I think... I want to be able to do those "ground-plane" type foils...

Should be able to do that in 6.5. Just create a polygon the size of the PCB then right-click > name > GND, click the rats nest button and voila. Just be sure to then right-click the polygon and set its isolation to something like .016 or .024 or whatever distance works best for you.

I get an "invalid Polygon"...  Maybe we can PM

I'm using 7.1 and I use ground pours all the time, microwave work demands it, but I did them in 5.4 too so maybe it a setting in your design rules or something.  Of course while I'm ok at using Eagle, I have to ask a guy here at work how to fix it when it goes wrong, so I'm not the greatest guy to help troubleshoot for you.

[italianguy63]

I finally got it to take.  How absolutely awesome!  Thank you gentlemen!!  MC

[karbomusic]

I finally got it to take.  How absolutely awesome!  Thank you gentlemen!!  MC

Suuhhweeet!

[italianguy63]

Who says an old dog can't learn new tricks!!   

[anotherjim]

Neat work.

May I ask why the name "Tisdale"?

Oh, and here's an Invalid Poly gone