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Topic: Ringo3 board building (design by matseng) (Read 13439 times) previous topic - next topic

Ringo3 board building (design by matseng)

Few days ago I received one ringo3 PCB from forum member matseng. It's having 60+60+12 LEDs (ss,mm,hh). The board design is nice as you can see in

Now, I've gathered most components of it, and I soldered it in about 2 hours (I should have checked those LEDs before soldering, I found 8 LEDs to be dead and had to replace them).
Since this is multiplexed matrix, we cannot have individual control over all of the LEDs at the same time. I need to fast switch between rows (as in schematics), or can have other ideas(give me ideas).
[attachment=0]
I used some 0603 caps in place because I had 22pf only in 0603 and 1206.
Now I have to add the resistors (100Ohms should be OK) and MOSFETs. MOSFETs from china(ebay) haven't reached me yet. I guess I will install some NPN like BC548 in place of the N-ch mosfets if it takes too much time to arrive.
Still learning
-Arup

Re: Ringo3 board building (design by masteng)

Reply #1
Ah, even I haven't built it myself yet.  This is actually the first time anyone is using my pcb's before me.  Way to go Arup!

BC547 or 2n222 should work instead of the nfet 2n7000 , but you must then connect a resistor between the base and the avr or else the avr pins basically will be shorted to ground.

Being able to get rid of the base resistors one of the major reasons that I use nfets instead if BJT's.  Less losses (for low and medium currents at least) and the ability to remove the base resistor.  And the price for the 2n7000 is about the same as for a bc547.

One disadvantage of using fets is that during reset of the mcu the output pins are floating and might activate the transistors for a while, this doesn't happen with a bjt. In most cases this is not a major issue...

Re: Ringo3 board building (design by masteng)

Reply #2
[quote author="matseng"]One disadvantage of using fets is that during reset of the mcu the output pins are floating and might activate the transistors for a while, this doesn't happen with a bjt. In most cases this is not a major issue...[/quote]
I started to love MOSFETs after using them in a couple of SMPS projects. I just get rid of the voltage drop and related loss as I always put a pulldown resistor to the gate of the MOSFET (or pullup for p-channel ones) to get rid of that floating pin and accidental activation problem.

Re: Ringo3 board building (design by matseng)

Reply #3
I was just going to solder some BC548 to test it with some code, but found a major problem. The LED's anode bus (CA1-BUS,.....,CA5-BUS) is connected to the drain of MOSFET or in the other case it's connected to Collector of BJT. But since it was n-mos or npn, the LED's anode won't get +ve supply; also there is no other pullup.
I guess I have to desolder every LED and reverse them then resolder. :(
Still learning
-Arup

Re: Ringo3 board building (design by matseng)

Reply #4
Ah, that's a major bummer.  I've must have been both drunk and having multiple brain farts while doing the design....

But how did you mount the leds?  The + & - markings on the pcb is wrong as as the schematics, but if you've mounted the leds according to the outline on the pcb  - the phased off edge of the led inwards it should be ok.

Re: Ringo3 board building (design by matseng)

Reply #5
[quote author="matseng"]Ah, that's a major bummer.  I've must have been both drunk and having multiple brain farts while doing the design....[/quote] LOL

I actually soldered those LEDs by the +,- signs as on the PCB. I was going to install the NPN BJTs then noticed that the trace from collector goes to led's +ve which it shouldn't be. Opened the schematics to confirm it and saw all LEDs are upside down. Will take a break of 2days before I try to repair those because it's gonna take much more time because completely desoldering the pipes (vias) is a bit time taking work.
Still learning
-Arup

Re: Ringo3 board building (design by matseng)

Reply #6
Things went worse.
Some PCB tracks were lifted and even some vias came off, hanging with tracks. The fix is not that easy now. If it was SMT, no headache of TH vias would be there.

Now I have to find a way to remake those vias by jumpering(probably) as leds have pins beneath them so both side soldering is not possible.
Still learning
-Arup

Re: Ringo3 board building (design by matseng)

Reply #7
I'll send you a new pcb.....  That will probably be the best solution.

Re: Ringo3 board building (design by matseng)

Reply #8
[quote author="matseng"]I'll send you a new pcb.....  That will probably be the best solution.[/quote]
Thanks.
Still learning
-Arup

Re: Ringo3 board building (design by matseng)

Reply #9
The new Ringo3 PCB is on its way to you now.  I added PCB's for the LOpen and the Simonette ( download/file.php?id=8456&mode=view ) if you get bored some day and want to solder them up.

Re: Ringo3 board building (design by matseng)

Reply #10
Looks like half process done...


[attachment=0]


Coding remaining...........................
Still learning
-Arup

Re: Ringo3 board building (design by matseng)

Reply #11
I'm dying to build one of these. I found the Eagle file, but not the code. Can you guys post a sketch for this?

Thanks.