Pyrotechnic firing sequencer

[dodgey]

Thanks SE. I have a circuit diag all ready to go (like you said, xtal, pull down resistors and transistors - and relays) . trouble is, I want to etch a shiney nice PCB, but when I use PCB wiz or similar, I have trouble making the tracks (so they don't run over each other) - I'm looking for software to help me. I want to be able to design it in a sim so the PCB s/w will route if for me...

 

[Someone Electro]

do you have an breadbord to test your design.becose if somting isent working as you desierd you can change the circuit esaly by pluging in componetes in difrent ways


be avere that a tiny electrostatic discharge can fry a PIC instantly! so ground yourself to prevent that (have an alufoil strap aound your wrist and conect th alufoil to an wather pipe,groun conecotr on the mains plug,your computer case...(anything that has an ground conecon)).

 

[dodgey]

Don't worry. got me breadboard for prototyping Work with computers a lot so I'm no stranger to esd.

Out of interest, below is the link to the project I'm using.

https://tomscarff.tripod.com/midi_24op/midi_to_24_outputs.htm

One or two things suprise me..

a) On his schematic, he lists 2 x 100nf and 2 x 33pf caps, yet when you look at his finished board photo I can see the 4 brown caps which must be them ,but also what looks to me like 2 x elect. caps, at the top by the regulator.?

Also there is a long "giant" looking brown cap by the crystal, running vertically?

any ideas?

p.s. getting on well with the PCB layout. Seemed simpler in the end to do the routing manually myself.!

 

[Dr.EM]

I reckon the electrolytics are to filter the power supply, and the giant cap is a resistor array. Any ideas?

 

[Someone Electro]

i think the resitors are there to limit the curent so if an ouput gets short circuted it wont fry the PIC

And yes the two electrolics are to filter the suply (the litle ceramic one too to filter hich freq. noise)as you know PICs need an realy stable power suply becose noise and voltage slumps can reset or freze the PIC (thats why i have an 1000uF and an 100nF cap on the power rails)

you still need somting to swith 0.5A,an MOSFET or power trasistor (i got some cheap trasistors that handle 600mA whith no heatsink)

 

[dodgey]

Thanks Guys. So you think I should put the electrolytics in parallel with the ceramics by the regulator? (obviously I'll test all this on my bread board).

Started learning PIC the last few days. Getting there. Thing is my basic electronics is a little weak. Think it's time to buy a book so I properly understand what certain components do. God how I wish I was this keen to learn when I was at school!

As for getting output, was planning to then use his relay board idea.

https://tomscarff.tripod.com/relay_changeover/relay_changeover.htm

I've got mini relays that only requite about 250ma.

Incidentally, I want to use relays because it means I can hook the board direct to the buttons on my firing system, and therefore keep it simple and use the existing battery for firing etc.

When I', happy with this, and when I can happily code the PIC I want, I'm planning to make a stand alone sequencer. At that stage I'll try the FETS I've got and fire directly to ematches.

Nigel G - I can't get emails form your BBS ro complete the registration :-(

 

[Nigel Goodwin]

Nigel G - I can't get emails form your BBS ro complete the registration :-(

PM me with the username you used, and I'll activate it for you!.

 

[clalulu]

HI!!!! I' ITALIAN AND I WANT CONSTRUCT THIS SEQUENCER FOR MY FIREWORKS!.I AM TRYING TO CREATE ALSO THIS SEQUENCER BUT I AM HAVING PROBLEMS. I HAVE NOT UNDERSTOOD STILL WHICH CIRCUIT TO USE AND and I would want to know if someone has already a pcb saved and if they exist gia of the circuits pre-stampa you that they have the adjustable modality sequencer.
please you help me that it is from that I am trying!
thanks