First Production Board Done

[LyleCaldwell]

Well, except for the leads to pots and switches.  But I still feel good looking at it.  Just 49 more to do (for this batch)...

[John Lyons]

Looks really nice and quite an undertaking! I've heard those initial sound clips..looking forward to more.

John

[LyleCaldwell]

Thanks John!  That reminds me, I need to email you about a wooden enclosure for something else...

[pi22seven]

Man, that's like looking at porn! Good job!

[Toney]

Mmm mmm tasty, ............er....what is it?

Who made those boards?

They look excellent.

[LyleCaldwell]

It's a Triad preamp/fx integrator/boost - go here for more info:  www.psionicaudio.com.

The board is ExpressPCB's production service with double layered, plate through, silkscreened and solder masked board.  I'm very pleased with it.

[JimRayden]

What program'd you use to make the layout for them? What do they accept?

-----------
Jimbo

[LyleCaldwell]

ExpressPCB has their own free software that works well, but they also accept AutoCAD files.

[JimRayden]

Great, I might be ordering a bunch. I broke the drill bit for PCB holes today and got real fed up.

Great looking board by the way!

----------
Jimbo

[Peter Snowberg]

Looks great Lyle!

I've used ExpressPCB a bunch of times over the last few years and I've been quite pleased every time. Registration is always great, features are well defined, copper is nice and thick, solder coating is always clean, and the mask is always solid.

I've had plenty of bad experiences with smaller board houses so I really appreciate it when things are more or less perfect. 

Now if they only had an ExpressPCB<->Eagle converter... 

[Satch12879]

AutoCAD, really? That's an odd format to accept; not standard at all for electronics work.

[LyleCaldwell]

Isn't that what a DXF file is?

[Peter Snowberg]

Yep. AutoCAD is pretty standard.

(local pride: I live in the town where it was born)

[Unbeliever]

Looks nice.

What kind of power supply is on board? The reason I ask is that you might be able to lose the heatsinks on the regulators if you aren't drawing too much current, especially if you change the PCB layout so the PCB itself forms a heatsink (i.e. have raw metal underneath the regulators). I've done this before, and it works really well. Guess you might only save $1 or so per device, but ... well ... just a thought.

[LyleCaldwell]

It's a modified version of the Rane public supply which doubles 9vac, bridge rectifies it, then you use a positive and negative regulator to get whatever output you want, in my case +15vdc and -15vdc.  The heatsink on the 7915 (-15vdc) isn't needed, as it only goes to the circuit in the pedal, which only pulls a bit under 100ma.  So I will skip the heatsink the 7915 on the other boards.  But the 7815 (+15vdc) feeds both the circuit and an LM317 for supplying up to 900ma of external 9.6vdc.  So the 7815 and LM317 need the heatsinks.  It's extremely well filtered and quiet.  Nice, though large.  I usually only use it in rack mixers, but this was the best sounding way to give this circuit 30vdc from rail to rail and 9vac isn't that uncommon for pedalboards any more.

I thought about using large copper planes on the PCB, but given how cheap To-220 heatsinks are and that they are more effective, I went with the heatsinks.  But these are a pain - gotta search Mouser for something easier.  With these you have to pry up the middle fins to fit the TO-220 inside, and you have to spread the large fins out to be able to get the screw in the hole, and then you have to move the fins back once it's in place.  Too many PITA steps.

[Paul Perry (Frostwave)]

It's a modified version of the Rane public supply which doubles 9vac, bridge rectifies it, then you use a positive and negative regulator to get whatever output you want, in my case +15vdc and -15vdc. 

I don't understand the "doubles 9v AC" part.... is there a transformer involved?
Secondly, if you ever want to 'share' a 9v AC supply with another unit, remember it is quite possible (probable) that one side of the 9v AC is connected to ground in the other unit, either directly or via some rectifier arrangement that is going to give smoke and tears (in that order).

[Paul Perry (Frostwave)]

It's a modified version of the Rane public supply which doubles 9vac, bridge rectifies it, then you use a positive and negative regulator to get whatever output you want, in my case +15vdc and -15vdc. 

I don't understand the "doubles 9v AC" part.... is there a transformer involved?
Secondly, if you ever want to 'share' a 9v AC supply with another unit, remember it is quite possible (probable) that one side of the 9v AC is connected to ground in the other unit, either directly or via some rectifier arrangement that is going to give smoke and tears (in that order).

[LyleCaldwell]

The incoming 9vac, which is not shared with any other supply, is roughly  doubled and then the DC rectification adds a bit more voltage.

Here's the Rane that I used as a basis:

[LyleCaldwell]

One of the guys testing the prototype did a video clip of his first experiments, just showing the amount of gain available from "just" the preamp, without the additional boost kicked in.  This is Strat > Triad > Verbzilla (which I think was set too wet) > Vox AC30CC. 

He's going to do more clips showing the different stages and series/parallel effects loop in the next few days.

Right click and save if you aren't using IE.

www.psionicaudio.com/video/wow.wmv

[Unbeliever]

Thanks for that power supply schematic - looks like a handy way of getting +/-15V from old modem power supply's etc. Paul's warning is valid, but if you only have one output from the 910VAC wallwart then it wouldn't be a problem.