PICKINI V4 - an easy to build, self adjusting PI detector

[BC547]

Nice looking board !

I can see you used a range of different 100 nF caps. In theory they should all be ceramic, but this most probably won't effect the functionality.
I also never placed a heatsink on the MOSFET. With the standard 100 microsecond pulse width, that should not be a problem.

Regards,
- Bernard

[sinclairuser]

hi all, not far off finishing now.
aly.

[BC547]

The 'short term' plans for this project would be to include a bluetooth 9600bps serial interface to allow anyone to change all settings - including temporal/voltage sampling - and store these settings in eeprom. When you look at the schematic of the felezjoo detector and pickini v1, there are many similarities. The same hardware could be used for pulse width measurement or classic voltage sampling

[scrungy_doolittle]

I just hope the OP will take this to heart, and relay out the board.... to include the ICSP pins on the board.

[waltr]

^ Exactly. Just Flashing code into the PIC the first time is worth putting the ICSP headed on the PCB.

[scrungy_doolittle]

My point was that the pickini, and the vdi and any other pic based project, needs the pickit programming header laid out on the board. Having worked extensively with the RN4020 blue tooth module, I can tell you that you don't want to try to use it. It is buggier than you can imagine. I worked on a medical instrument that used a PIC24 to control 2 8051 based electric stimulators (which by the way, used a flyback for generating a +/- 700 volt, nano amp stim pulse). An app on a tablet was supposed to communicate with a PIC24 through the RN4020, using the MDP serial protocol. What a nightmare!

[BC547]

I agree that having an ICSP header is easy to reprogram the PIC without removing the chip. However when you are playing with settings like pulse delay/width, I would prefer a bluetooth serial link and modify settings via a smartphone and an app like blueterm + store these settins in the PIC EEPROM. This allows for generic fixed code and flexible settings parameters. The code itself could be fixed and simple: generate a tx pulse (setting = pulse width), take a sample some time later ( setting =pulse delay), etc..
This way, anyone can adapt all settings personally. I usually use the bluetooth module only for debugging.

[waltr]

the problem I have with these pics is that they require a header to program. Now: how about just putting a 6 pin .1 inch header on the board and hooking it to the correct pins, so those of us with an ICD3 or PIKIT3 can simply program the chip in place?

I agree and do put the ICSP header on all my PIC project PCBs.Sure makes code loads and updates very easy and quick.
I can simply open the box of my HH PI detector, plug in the PICKit2 and a few mouse clicks have code updated.

[scrungy_doolittle]

the problem I have with these pics is that they require a header to program. Now: how about just putting a 6 pin .1 inch header on the board and hooking it to the correct pins, so those of us with an ICD3 or PIKIT3 can simply program the chip in place?

[sinclairuser]

There is a little circuit(about 5 components) which provides a soft start upon switch on. Maybe it will be good for use here or for some other circuit. It slowly charges the capacitor thus limiting inrush current. If used in conjunction with regulator....well have a look:

thanks DB,

thanks bernard,

aly.

[BC547]

Another option to limit the inrush current passively is an NTC thermistor between the battery and the circuit.
At startup = normal temperature ( 25 C) it has a relatively high resistance to limit the inrush current and as current is flowing through it, resistance will decrease.
As described here e.g. : http://www.farnell.com/datasheets/18...SAAEgJgHPD_BwE

[dbanner]

hi all i'm currently tinkering around with the pickini, in my cap stash i have 3300uf 50v elcos, 3300uf 25v and 2200uf 16v,
but not 2200uf 25v, so what do you all think should i use 3300 25v or2200 16v?.
normally i would use the 3300uf at 25v, instead of 2200uf 16v better to use a slightly bigger cap than a lower voltage version.
but reading through the thread turn on inrush current can be a problem here, will the extra capacitance be a problem, or will a 16v 2200uf cap be ok?.
thanks,
aly.

There is a little circuit(about 5 components) which provides a soft start upon switch on. Maybe it will be good for use here or for some other circuit. It slowly charges the capacitor thus limiting inrush current. If used in conjunction with regulator....well have a look:

[bernte_one]

nice finds, in germany some people do big fireworks for sylvester from that stuff

[sinclairuser]

thanks bernard.

[BC547]

16V is a little low with a 12V supply. I would use the 3300 uF / 35V.
Inrush current will be larger, but as long as you use a solid mechanical on/off switch or something similar combined with the sensitiivity potmeter, this should not be a problem.
The only time I experienced this as an issue was with a reed relay as on/off switch. After one cycle, the contacts were welded solid.