My =ultimate= multi-fx pedalboard...W.I.P

[Auke Haarsma]

I'm looking forward to the weekend, hopefully I can make some progress...

I've been struggling with a pos ground FuzzFace. It seems the prob is solved now, but since my PSU isn't finished yet, I can't tell for sure.

[jakenold]

Pong, get some MAX1044 IC's. I use them all the time when I'm building fuzz faces! They can covert your +9V to -9V, so you can run everything on the same PSU if it isn't isolated. Really usefull if you are making a FF for a friend.

Kind regards, Jake

[Auke Haarsma]

Thanks for the tip. My initial PSU for this project included MAX1044's, but the couldn't supply the current I needed  (I used them also as a voltage doubler to get 18V).

For a single FF the would indeed suffice. But since I also want to have an ps ground output for the eventual external pos ground fx, I can't use a MAX1044 in this project.

[jakenold]

I've made some cables to my power supply, with the MAX1044 circuit built into them, in a tiny plastic box. That way I can just connect a cable to almost any kind of power supply and get +18V or -9V.

That might be an idea.

Kind regards, Jake

[Auke Haarsma]

that's a really cool idea!

[stephanovitch]

The LT1054 have more ouput current (100ma) and are pin to pin compatible with max1044.

[Auke Haarsma]

stephanovitch: Thanks for the tip. I couldn't locate a supplier in the Netherlands for that one.

Today I worked some on the power supply. Here's the schematic:



Notes:
-on the left the mains are connected (230v).
-The two secondaries will (ofcourse) get their own ground. GND of the first secondary is not connected to GND of the 2nd secondary.

The AC is being filtered before entering the transformer.
100R+100nF is for some filtering. 1000uF to prevent ripples.

My AC connector has 3 pins. the 3rd is for ground. But, where do I connect that pin to in this project? Should it be connected to the enclosure (assume a metal layer on the wood)?

Do you see any errors or ways to improve the filtering of this circuit?

[stephanovitch]

I think that this power supply schematics is more easy and classic:
http://www.neufgiga.com/index.php?m=c9ae77e8&a=7d397569&share=LNK14174723a743cfac8
What do you think about it?

[Auke Haarsma]

looks like the bipolar design at ggg.

I'll be using the 7809 and 7909 too, for my positive ground source. But in this case I want two +9V outputs, instead of a +9 and -9V output.

However, basicly the schematics are the same, mine has a little added filtering. Right?

[stephanovitch]

Oups, sorry  I haven't seen that is two 7809

[Auke Haarsma]

no problem. Your reply got me thinking anyway! I think if I implement the bipolar thing I can add another isolated output.

That will give me 4 isolated +9v outputs and 1 isolated -9V output. I also will have an isolated 15V output (for the pt80 and neovibe).

Merci beaucoup for thinking with me

[stephanovitch]

Thanks,
If your PCB have no ground plane, you can connect grounds to enclosure at the same point (or metal shield for wood box )

[Auke Haarsma]

PCBs made this weekend. I'll upload some pics later today.

[Auke Haarsma]

Populated the PS pcbs tonite.

Left to right: 9V, 18V, 9V. Each unit has two isolated and filtered outputs.


A topview of the bridgerectifier, filtering etc:


copperside shot, not my cleanest solderjob, but no shorts and it looks messier than it is...:



Next I have to put these in an enclosure. Is it advisable to put a metal encloser around these boards to isolate them from the rest of the multi-fx?

[Auke Haarsma]

An overview of all things prepared:




...and there's nothing wrong with one cow kissing another cow!

[Valoosj]

maybe you could show each effect separatly, with an identification?

[Auke Haarsma]

Check reply #35 of this thread. The Dr Boogey is not on that pic yet, but all the other fx are the same I think.

[Auke Haarsma]

So I ripped an old pc-psu apart... the enclosure seems quite useful 

Still in the 'idea'-stage ofcourse...



and I'll modify the height so my transformers just fit:



And I'll put a piece of plexi at the bottom of this enclosure and the PCBs to prevent shorts.

What do you say? If it works for a pc it can work for my multi-fx unit too... I guess... 

[Ry]

I did the same thing with a PC power supply and regulated pedal power.  It works very well.

[Auke Haarsma]

The last couple of weeks I've spent some time on the Powersupply. As said, it was my first time working with transformers etc, so it took me some time to figure out why it wasn't working as designed (since, ofcourse, it didn't work at first shot....). One transformer got hot, I had weird voltages on the outputs of the voltage regulators and a resistor got smoked....

The transformer getting hot was caused by a short. I thought I checked for shorts before assembling the PS, but must have overlooked one trace. The transformer didn't get hot anymore. I was worried I may have damaged something, but it all seemed to work. However, still I got weird voltages out of the regulators.

So I checked everything again. It's just a few parts...so it should be easy to spot my mistake...and it was... the mistake is proof that I'm still a n00b Instead of putting 100Ohm resistors in the filter-section....i used 100K Ohm resistors... No wonder I got weird voltages.

Swapped them out, put real 100 Ohm resistors back...fired it up...and voila! I got a nice 8.9V and 17.9V out of my regulators. Woohooo! But then....

I had the PS flipped upside down, so I could see the traces of the PCBs. Suddenly I saw smoke coming from below... Quickly I disconnected the powercable, flipped the PS over and checked for burning parts...I didn't see anything. Touched the transformers....not hot...touched the regulators...not hot. What's going on? I reconnected the powercable... after a couple of seconds...smoke! Then I saw where it was coming from... one of the freshly installed 100 Ohm resistors was really burning itself up in smoke. This got me wondering... Why is only 1 of the resistors burning? I have 5 of them all in almost equal positions... I removed the burned resistor, put a new one in. Fired it up...no smoke. Good voltages, no heat... Must have been my first bad resistor   (Do you remember your first bad resistor? )

Left it powerd on for an hour or so, just to check if it got hot...no problem here, it al stays very cool. Tested it with my PT-80, got a little voltage drop (not sure why) but the delay sounded very good. Still the Pwr Supply stayed very cool.

After these tests I boxed it up in the metal PC-PSU enclosure, held together with glue... No pics at this moment, but I'm sure they'll come.

I finally was able to start finishing my Neovibe (I needed the PwrSupply for that). Hopefully I can finish the vibe this weekend.

On a sidenote: My dad (who among other jobs works at a college) got me oscilloscope, a new one! I dropped him a line a couple of weeks ago, asking if he knew where to get a used, old scope. Last weekend we had a family-come-together and there he told me he got a new one... So now I have a brand new oscilloscope and also a much better DMM. I have no clue how to work with a oscilliscope yet but I'm sure I'll figure that out in the coming weeks/months. Tips and tricks, tutorials and websites are welcome