Dangerous Prototypes

I've been a bit busy the last couple of weeks but I've now finished my 22'nd Project A Week.  Maybe I have to change the name to PAAW instead (Project Almost A Week) ^_^

TraId is a really low cost version of the Part Ninja. It's made to only identify the pinout and type (NPN/PNP) of a transistor and display the results on eight LEDs.  Currently the firmware only handles BJTs but I think FETs should be possible as well.

The board is using a 14 pin PIC16LF1503 (less than a dollar in singles) and runs on a single CR2032 battery.  Just like the Part Ninja I'm using a 1K and a 300K resistor connected to each of the three transistor pins, putting out either 0 or 3 volts via the resistors and analyzing the resulting voltages using the PIC ADC.

The firmware, written in C, uses 1.3K of the available 2K so there's room for some more additions and improvements down the road.

There's no powerswitch on the board, the PIC simply goes into deep sleep after a while and is awakened by a press on the reset button. 

All parts are thru hole for easy soldering if I decide to make this into a kit some day.

All files for this project is available at https://github.com/SmallRoomLabs (https://github.com/SmallRoomLabs)

[attachment=2]

[attachment=1]

---

cool!, any pcb's for sale?

Very handy tool.

Can you detect the difference between bipolar and mosfet? I guess that might require some more hardware and to measure some analogue signals too. However, you should be able to detect the drain-source body-diode, which bipolar transistors do not have.

That reminds me, it will probably not function for junction-FETs and mosfets with a Vgs-th over 3V (often seen in high-power mosfets). Still very useful tool though ;-)


Something different: You have your URL link (http://smallroomlabs.com/ (http://smallroomlabs.com/)) on each PCB, but there is nothing on the site...

Hi Mats;
  very cool tool.
I like the different footprints.
On the sot-23 could you put a fake component behind it as a backrest?

If you sell them sign me up for one.

btw I just checked your site:
"July 17,2013 - The SmallRoomLabs site has been hacked. Currently restoring from backup and patching holes. Please come back later."

Mick M

@neslekkim:  They will be for sale at Tindie, but I need to order more pcbs first so it will take about two weeks.

@Bertho: The hardware connection the DUT is basically the same as on the Part Ninja, so I think it should be possible to handle mosfets correctly, but as you say - having a vcc of only three volts limits the fets to low Vgs models.  Still, better than nothing :)

@MickM: Yes, that might be a good idea.  Maybe just two 0.7mm holes at either side of the the top pad so a piece of wire can be soldered across it as a "stopper".  The cut off leads from the LEDs are square and will probably be a perfect stopper block.

Yes, my site was hacked so I took it down, and as the lazyass procrastinator that I am I haven't put it back in place yet. :-(

The Eagle and Firmware files are at my github as usual  - https://github.com/SmallRoomLabs (https://github.com/SmallRoomLabs)

I too am interested in the kit. Maybe an upgraded unit could have a voltage booster to 5 volts? This could be enabled by the processor, then disabled in sleep mode. You could then test the MOSFET's, et. al.

I added some tests for N-channel MOSFETs in the firmware and it seems like 2n7000, IRLZ14 and IRF540 works fine, but I can't say how marginal the results are.  Unfortunately I can't find any P-type in my bins, I'll order some so I have them on Tuesday for further testing.

@fredmatic1: To make it better for FETs the PIC16LF1503 can be changed into a PIC16F1503 and the CR2032 battery could be replaced with two stacked CR2016.

This will overvoltage the PIC a bit from the nominal max of 5.0 volts, but the datasheet says that Absolute Maximum voltage is 6.5 volts so 6 volts should probably not be a big issue here.  This is just a consumer-grade plaything - not NASA or a Life Support device.... :)

[quote author="matseng"]This will overvoltage the PIC a bit from the nominal max of 5.0 volts, but the datasheet says that Absolute Maximum voltage is 6.5 volts so 6 volts should probably not be a big issue here.[/quote]
That is playing with fire though. Fresh cells with a nominal 3V output go up to 3.3V in open circuit conditions (and that is by design). That would worst case be 6.6V at ultra low loads (like sleep) and is over the max. ratings. Surely, the micro-controller will start to break down and the additional current would be a load on the cells and let the voltage drop a bit, but that is not really healthy.

Cheap ghetto solution might be two diodes to drop the voltage a bit.  I reckon that a single diodes drop in the nanoamp range might not bring the 6.6 down enough.

[quote author="matseng"]Cheap ghetto solution might be two diodes to drop the voltage a bit.  I reckon that a single diodes drop in the nanoamp range might not bring the 6.6 down enough.[/quote]
It might be just enough though. If you have a (very) high impedance voltmeter, then you can test it and measure the voltage drop across the diode(s) at sleep conditions. You probably get 50..200mV for a 1N4148. Adding a 10..50M resistor over the micro-controller supply may actually improve the situation.

The firmware have some lcd code, and commented include that can be uncommented for lcd debugging, what type of lcd is used, and where to connect it?
Or is the pic to small for that?

The pic have a spare pin connected to the via below pin 7.  I have it connected to a 2x8 LCD with a 1-wire serial "roman black" backback as described in this thread: viewtopic.php?f=4&t=4335&p=42647 (http://dangerousprototypes.com/forum/viewtopic.php?f=4&t=4335&p=42647)

I'll replace the code with code for my PIC12F1501-based version of McLaren's serial display backpack as I wrote about in the last post in that thread.

Since the Roman Black-based backpack is "dumb" (essentially just a shift register) the PIC needs to have all the LCD initialization code and other stuffs that bloat the code a bit.  So I don't think all of the TraId code will fit with the LCD code at the same time now. 

When I change to the "smart" McLaren PIC-based backback the LCD code will be much smaller and have a better chance to fit together with the full TraId code.

Whohoo!  Hack A Day.... ^_^ http://hackaday.com/2013/09/14/organizing-transistors/ (http://hackaday.com/2013/09/14/organizing-transistors/)

Congrats, Always good to get more exposure.
Did you send in a link or did they pick it up from someone else/elsewhere?

[edit: this post overflowed my byte-counter ;-)]

Thanks.

No, I'm completely innocent in this case - someone else must have sent in a tip, or they are surfing the interwebs themselves.

Nice. Post 0x100 or as I'd say $100. ;-}

Great project ,count me in for a pcb also ,& thanks for a great tool ..