Jan's Plasma Speaker! Woo! / Projects / Forums

Forums

4hv.org :: Forums :: Projects

« Previous topic | Next topic »

Jan's Plasma Speaker! Woo!

1 2 next

Move Thread

LAN_403

indiana

Sat Mar 28 2009, 02:13AM

Registered Member #2009 Joined: Tue Mar 03 2009, 07:07PM
Location:
Posts: 43

I'm really excited to be posting my first project on here.

I've got all of the components, and I've put together an eagle file for it.

Getting ready to hand make the pcb with a toner transfer.

Would anyone be willing to take a second look at my pcb against the schematic, and tell me if there are any glaringly obvious mistakes?

Thank you!

I'll post as I move along in the build.

indiana

Sat Mar 28 2009, 02:15AM

Registered Member #2009 Joined: Tue Mar 03 2009, 07:07PM
Location:
Posts: 43

ah, bummer.

sorry for the double post, it wouldn't let me post the .brd file.

try a .png

rp181

Sat Mar 28 2009, 02:26AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529

Board looks good as far as i can tell. How are you doing your board? Self etch, light sensitive, or sending it out? For future reference, you can click the pencil on the header of your post to edit it.

Looking forward to the end piece =)

aonomus

Sat Mar 28 2009, 02:29AM

Registered Member #1497 Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801

Might I make a few suggestions about the board design:

1. Make the trace corners angled at 45 degrees where you can, it makes toner transfer easier.
2. Add a ground plane, it also makes toner transfer easier
3. Strongly consider adding optoisolation, even a simple 4n25/4n35 should be fast enough for audio frequencies.
4. Make the PCB size larger and add mounting holes, a loose PCB on a workbench doesn't always work out well...
5. Since your IC has integrated transistors, think about moving the small electrolytics (to the top right of the IC) further away to give clearance for a DIP16 socket
6. Is that 3.3nF capacitor a *little* too big or is it just me...

Dr. Dark Current

Sat Mar 28 2009, 09:12AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

If you groud the circuit to mains Earth, then there's no need for any isolation IMO.

Edit: Be careful when tuning that circuit, when any of the parameters gets too far off (which can happen really easily mind you), something goes "pop". Consider adding some kind of current limiting (a light bulb) in series with the power part of the circuit for testing. I would not say its a beginner project and if you're going for the bridge version, you'll most likely need a scope.

If you need help with the circuit/tuning, just ask or send me a PM.

indiana

Sun Mar 29 2009, 07:59AM

Registered Member #2009 Joined: Tue Mar 03 2009, 07:07PM
Location:
Posts: 43

Thanks so much for the advice.

I've applied it thoroughly... I believe... ;)

the 3.3nf cap package is just for the pin spacing. the cap is much smaller. :)

this version is for the "not as great" output.

i'm going to give it a try this way, and then build another one with the full bridge. I have a scope coming in the mail. My old one ate it. :(

I think this version is a much better build.

What'd'ya think?

1238313563 2009 FT66538 Plasma Speaker 3

Dr. Dark Current

Sun Mar 29 2009, 08:21AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Audio input should be to Pin 6 (check the schematic). Connect pin 3 to GND. I can't see any gate resistor but should be OK without it.

indiana

Mon Mar 30 2009, 09:48PM

Registered Member #2009 Joined: Tue Mar 03 2009, 07:07PM
Location:
Posts: 43

yep. messed it up changing over to curved traces.

connected 3 to ground, and cleaned it up a bit, put in the resistor as well for good measure.

input now connected to pin 6.

thanks again. i think it's all set now.

edit: realized there's no parts images on that file... with i knew how to change the file i uploaded... or upload a new one to the same spot...
anyway, it's all clear enough save the 10r resistor, it's the two vias right above the gate of the fet.

1238449683 2009 FT66538 Plasma Speaker Print

Dr. Dark Current

Tue Mar 31 2009, 06:28AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

I think you should have a look at the schematic again; the 2.2uF cap is just after the input, then there is the 10k pot in series with a 2.2k resistor to ground, then it goes to pin 6.
It will not work like you connected it now.

P.S. here is the original link to schematic (which has some bug fixes)

indiana

Wed Apr 01 2009, 06:30PM

Registered Member #2009 Joined: Tue Mar 03 2009, 07:07PM
Location:
Posts: 43

shoot. lol

tricky. in making the new connections i'd erase a line and redraw it... and it looks like i managed to mangle it a bit.

getting the ground plane to appear in eagle is what was causing me a lot of grief. seems like to get it to reconnect everything you have to make a new bit of trace on what should be the ground plane and rename it gnd (considering you've renamed all of the other ground traces gnd as well) then the whole plane shows up again.

in the midst of all that, looks like i screwed up some other bits.

'all right though... learning in leaps and bounds. thanks dr. for all of your help. I re-routed the trace from the signal filter cap (it was erroneously going to pin 5) and connected it to the 2.2k resistor.

is it okay to connect it the way i've done here? it kind of goes from the filter cap to the resistor and to pin 6 "at the same time". would it make a difference if i reoriented the cap to be closer to the resistor and further from the pin?

seems like the signal is going to hit both so fast it wouldn't make a difference.... am i correct in saying that?

1238610473 2009 FT66538 Plasma Speaker 3

1 2 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob