DIY-Central.com - Go Create something! - PCB Design, Electronics

Finally finished one channel and did some testing.... THE MOMENT OF TRUTH is coming! Will it work or not???

Woohoooo!!!!! YES! 

At first I wasn't getting any signal and was in a bit of panic... I'm thinking "oh no... what did I do wrong?" 

Told myself I need to calm down and re-check everything step by step. Found out I have a loose connection since everything is just temporarily affixed with tape and alligator clips. Secured that connection and now we have continuity.

Device Under Test


Then I heard music... coming from my signal source... YES! It works and passes signal. Sounds good too! Pretty stoked about it.  Check the gain settings, it works... check the trim, it works.  I tested it with a line level input and an SM57 dynamic mic, and yes, sounds great.  I haven't tested it yet with condenser mics since I don't have the switchboard hooked up yet... (the switchboard has the 48V phantom power converter).

After an hour of music listening, hooked it up to my signal gen and oscilloscope to see out how things are. 

Check it out... here's the square wave response at 1Khz.  Notice how clean and sharp the square wave response is... no ringing, oscillations or instability at either the rising and falling edges!

Square Wave Response 1Khz


Did some output measurements while we're at it... how high an output can we go before clipping or instability. I'm not expecting it to be high (like +27/28dBu) since we're not using high supply voltages here, just a DC-DC converter PSU... but let's see what can we get...

Not bad.... not bad at all.  Some readings....

15Hz @ 32Vpp      = +23 dBu
20Hz @ 35.6Vpp   = +24dBu
1Khz @ 37.7Vpp    = +24.7 dBu
22Khz @ 31.1Vpp   = +23dBu
100Khz @ 24.4Vpp = +20dBu
200Khz @ 14.65Vpp = +16.5dBu

Output waveform at 100Khz.



What's the Next Step?

Build the 2nd channel on the TS-2 preamp board, then test together the Motherboard and Switchboard...
Metalwork/CNC for the case, verify measurements and hole locations
 
So far, I'm pretty pleased with how everything is working out, from concept and design on paper, to CAD, to a working prototype.

Anyways... finally got some time tonight to do some work on the motherboard.

First, populated the PSU section to see if it works... yup, A.O.K.  (had to jumper the switch temporarily since the motherboard isn't hooked to the switchboard.)

So far so good, the switchboard, 48V section, and now the DC-DC section are all working fine.

Work done so far... all resistors, zeners and diodes stuffed.


Tomorrow after church service, I'll solder the caps, IC sockets, pots and switches and XLRs, then start testing.

Built the TS-2 switchboard PCB, tested the 48V phantom power section and it works A.O.K!

LEDs will be mounted under the board.

I can already see a few minor changes to the board design... need to push the switches a bit more forward, maybe by 0.1"

The height clearance is perfect... about 1mm for the caps and about 2mm for the switches between these parts and the celing height of the case. Real tight... 

Again, here's the initial design that existed only on the computer.


And here it is, in real life   (with a few minor changes as you can see.)


Now, off to build the main motherboard. 

UPDATED:

New prototype boards came in today... wohoo!


Let's do some test fittings...

The (2) VU Meters


and oh yeah.... 2 input transformers.


This is the switchboard...


A preview of things to come...


Next step: Build a prototype using these new boards and see if it works.