Author Topic: mojo2  (Read 23882 times)

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Offline yeo

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mojo2
« on: October 26, 2010, 11:30:56 PM »
hi guys

lest you guys think i've gone off planet earth, i'm still alive and kicking. been to 3 countries the past 2 months and all this travelling is taking a toll on me.

finally back home but... lethargy kicks in... dang!

anyway, here's a rough but not ready pcb layout for mojo2.

changes from mojo:

1. slots for regulators. one for each channel of i/v stage, one for 12vdc, then feeds ccs2, then feeds 5v and 0.83v regulator. ditched the ccs + string of diode scheme.

2. incorporated the marvellous 3 transistor tweak by paul n. as you can see, due to space constraints, considering smd resistors here.


guys

any input? if you have any comments or changes to mojo you want to see, please highlight now.

hope to wrap this up this week and send for fab.

thx!

yeo
ps: anyone willing to proof read? of course, you'll get the mojo2 kit free.






Offline ernesternest

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Re: mojo2
« Reply #1 on: October 27, 2010, 01:20:50 PM »
Hi Yeo,

preliminary let me be a bit off topic and say, I like my Monica/ Mojo/ Ultravox combi right from the beginning. But the more I modified mojo and psu (Superteddys and discrete CCS), the more I liked it and meanwhile the sound is really very impressive.

Good to see, you are implementing the 3 transistor mod. Much better - and really a bit tricky if eyes are already slightly older.....

So you ask for proposals and wishes - christmas it not too far ::)   ok.

# I do not own Blackgates for decoupling. Other good caps are much bigger, so reservating some space for dedicated foil types would be a great thing. If not possible due to limited space ? why? next point might help

# changing current B1 to a B1 with symmetric PSU would allow the usage of tiny perfect cheap small caps for decoupling. I know, this would make PSU more difficult, but i'm pretty sure, sound would further improve.

# 2 more bores for 2 more screws

# Please keep an option not to use PH regs - which could mean, option for integrated regs or good contacts for external and selfmade solutions.

Well, ahh,  thanks for starting mojo 2. Btw what does meand "proof read"?

Regards Ernst   



 

Offline yeo

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Re: mojo2
« Reply #2 on: October 27, 2010, 06:13:15 PM »
hi ernst

thanks for your feedback.

ok. i can make the size larger for the tda1545 power supply caps. however, it's worth going for the black gates in super e config. quite a major upgrade here.

i'm not so sure of going dual supply b1. will stick with the current one.

i'll try to find space to accomodate more holes.

currently you could use whatever reg you want to for 18vdc, 12vdc and 5vdc. however the 0.83vdc reg, i'm aware of anyone offering this other than paul hynes.

i guess i could offer a small pcb which utilizes the original ccs fed to string of diodes as a cheap 0.83v reg.

anyone, any comments?

yeo

Offline yeo

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Re: mojo2
« Reply #3 on: October 27, 2010, 06:38:59 PM »

oh, what i meant by proof read is help me check my wiring in case i got it wrong. i'm terrible at this.

yeo

Offline yeo

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Re: mojo2
« Reply #4 on: October 27, 2010, 07:23:10 PM »
hi guys

more changes. i think it looks much better now.

may have to resort to smd resistors for the 3 transistor mod.

any comments?

yeo

Offline ernesternest

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Re: mojo2
« Reply #5 on: October 28, 2010, 12:13:22 AM »
hi ernst

thanks for your feedback.

ok. i can make the size larger for the tda1545 power supply caps. however, it's worth going for the black gates in super e config. quite a major upgrade here.


Yeo, actually I haven't meant the TDA1545 decoupling, but the possibility to use 4.7 µF foils instead of the 4.7µF Blackgate N super e's just because I don't have them and further have no idea where to get. Future customers probably wouldn't have either, would they?

Currently in my setup the signal runs through an Auricap MKP paralleled by a KP foil and the best styroflex I know.  Soundwise this is pretty audible but does look more like p2p wiring than pcb. That's the reason for my wish.


Indeed, I haven't tried to get the my regs to 0.84 V but I'm going to. So far I still use one diode of the former string fed by a 20mA FET.  Very nice sound even I just get 0,79 V for Vref.


I know shourt traces are of major importance, an probably the reason for keeping the board small. But with all the skyrocketing regulators the traces end up again long. And from a vibrational point of view.... Any possibility to integrate good regs direct into the board?


Cheers Ernst

Offline yeo

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Re: mojo2
« Reply #6 on: October 28, 2010, 11:50:06 PM »
hi ernst

alright! i have taken your input and incorporated some big pad holes for you to mount your choice of coupling cap. one end mounts on this board while the other can go to the output rca socket. so the cap can be as big as you want!  ;D

in order to accomodate all the extra components and still keep the path short, i have replaced some components with its surface mounted version. there are some smd ferrites too. all this should result in even better performance and lower noise.

if the voltage regulators are my design, you can be sure i'll include them in this pcb.  ;)

any comments before i proceed?

almost done now, just need to tidy up some more, then proof read, then fab.

yeo

Offline ernesternest

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Re: mojo2
« Reply #7 on: October 29, 2010, 12:11:55 AM »

any comments before i proceed?



Not from my side :)  - Thanks for the pads  :)

Cheers Ernst

Offline Paul N

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Re: mojo2
« Reply #8 on: October 29, 2010, 04:42:02 AM »
Hi Yeo

Am I missing something, or aren't the various reg pads supposed to connect to the circuit?!

Paul

Offline yeo

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Re: mojo2
« Reply #9 on: October 29, 2010, 05:23:02 AM »
Hi paul

Im not done yet. Just taking more input as i go along.

Do you have any comments on the  layout? Anything you would like to see?

Yeo

Offline weaver

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Re: mojo2
« Reply #10 on: October 30, 2010, 10:20:18 PM »
hi guys

more changes. i think it looks much better now.

may have to resort to smd resistors for the 3 transistor mod.

any comments?

yeo


I guess this means the transistors come pre-fitted - which is a very good thing as far as I'm concerned!

I've had a set of Paul's regs sat here waiting for this board for a while now - well done Yeo for finding the time.

Offline yeo

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Re: mojo2
« Reply #11 on: November 03, 2010, 12:22:18 AM »
hi guys

here's the completed version.

let me know if you have any comments.

yeo

Offline yeo

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Re: mojo2
« Reply #12 on: November 03, 2010, 12:23:28 AM »

with ground plane.

now time for proof reading, then send for fabrication.

had a minor scare when the notebook's motherboard failed on me the other day. fortunately the hard disk is okay!

yeo

Offline ian444

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Re: mojo2
« Reply #13 on: November 03, 2010, 02:16:34 AM »
Hi Yeo,

The 18VL reg is missing a track. I don't understand the pin-out of the various regs, the CCS makes sense but then the CCS output feeds the centre pin of the 5V reg, a bit confusing without knowing each reg's pinout. It looks like they are all the same, input/output/gnd for pins 1/2/3, or other way around?

I can look at checking the rest including the Paul N mod but need a fresh brain and that won't happen for another 3 days, my day job uses up most of my brain cells during the week...

Do you think there is enough room to squeeze in the 4th mounting hole?

Is it worth increasing the PCB size by say 10% to make it easier to build? And 10% bigger pads to make future mods easier?

Any chance of not being silver plated? Me and that silver plating do not get along very well :)

All looks good.

Ian.

Offline yeo

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Re: mojo2
« Reply #14 on: November 03, 2010, 06:23:19 AM »
hi ian

thx for your comments. nice catch on 18VL! i've fixed it.

the 3 regs are paul hynes regs. the 5v reg is actually "like a zener". it has 2 terminals only. i wired in 3 so if you put in audioslave, it's a "drop in".

the 18vr and 18vl i intend to use a modified audioslave for 18v operation.

i have a diyer who volunteered to check. i've sent the files to him so don't worry about it.

kind of hard to squeeze in another mounting hole though.

i can't increase the pcb size further as i've reached the limit of this freeware. to go larger (or more layers), i'll need to pay for the license. i enquired about the fee. was shocked to learn that it's >usd1500!

so what's your beef with silver plating? i'm all ears.

yeo