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Member Since 19 May 2012
Offline Last Active Oct 20 2013 11:14 AM

#42865 Netduino Plus, DIS(Direct Ignition System) and transistor help

Posted by Frankie on 06 January 2013 - 03:25 PM

Hi guys,


I just wanted to show you what we made with the netduino.

The netduino runs a small webserver accepting commands and produces JSON output. Im using an EventHandler factory and different mappers for the functions and hardware commonication.


Special thanks to Paul for helping with the transistor solution, NeoMika who's webserver project became the base for the Webservice, Wouter Huysentruit for the JSON parser and everybody on this forum for contributing.. The wiki was great help for getting the RGB leds working. thanks to Adam S from financecoding for sharing the code for the relayshield.


Near the end the code didnt got any nicer and had some resource locking issues, at a point the netduino would stall in debug mode while trigerring the DIS. I solved it by removing the webservers event handler and locking the trigger method.. not very nice but very functional when youre out of time.


anyway.. thanks a million for the support guys!


The controlunit for the canon, elevation adjustment, trigger and manual control

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more detail:

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Conrol unit:

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wifi accespoint(emergency solution as we couldend get the wifi running on the PI

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buttons/switches on the lid as wel as some gages and the touchscreen

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And here the webapp(loaded from the raspberry PI) that controlled it all.


Heppy new year and on to the next project

#37838 Netduino Plus, DIS(Direct Ignition System) and transistor help

Posted by Frankie on 23 October 2012 - 11:59 AM

Hi Frankie,

I'm not sure why, but I seem to have missed several updates on this post so I've got a bit out of step with all the updates and suggestions!

That last diagram looks right. Before I saw your diagram, I drew the attached this evening to show you what I meant.

1/ The circuit from the example you started with. The transistor is fully ON, so it has a voltage drop of about 0.3V and most of the 5V supply is available to the load. The base of the transistor is about 0.7V above the emitter. In this circuit the base voltage does not really matter.

2/ Using this to drive the DIS. Note that the negative on the 12V battery is NOT the same as the Gnd of the Netduino. The transistor bridges these signals when it turns ON.

3/ I think this is what you had initially. In this circuit the base emitter voltage matters. The emitter must be about 0.7V less than the base, and the base can only be 3.3V at the very most. Hence the emitter can only be 2.6V. (3.3V - 0.7V = 2.6V) So the load only gets 2.6V not 5V! The rest of the volts are lost across the transistor which acts as a resistor because it is not fully ON.

4/ Using a second (pnp) transistor. Now one npn transistor turns on a pnp transistor. In this case the 0.7V base voltage drops are both next to the rails, hence both transistors can turn on fully and the load gets the full voltage.

5/ How it would be applied to the DIS. Now all the circuit uses the same ground.

I hope this sheds light on the issues - Paul

PS, should I ask why you are making big sparks?

Thanks Paul, im now using schema 2.

On what I'm going to do with the spark, well that's a long story but ill try to keep it short.

Im from the eastern part of Holland and we have a tradition at the end of the year, we shoot with old milk canisters or other contraption. We use calcium carbide gas to do that.
heres a small video of what it is:

and some build like this:

Last year we made a gun on a trailer with a recoil system, modified a car jack and added a windscreen motor to it to make it go up and down etc.. etc. To get the accetelyne gas from the carbid you have to poor water over it and it starts to gass, because its a very messy and inefficient job we've build a gasifier that hold clean gas
The gassifier has 3 savety valves and never goes over 3 bar of pressure, its rated for 10bar pressure.

We build everything ourselves with scrap metal, using a angle grinders and welding equipment!

Anyway this year im going to automate it with the netduino, ive already programmed a platform on the netduino to handle Ajax requests and response in Json, created a whole interface layer for the hardware and services to manage it all. I created a request mapping class to map commands like ~ipaddres\firecontrol\armIgnition or ~ipaddres\jackcontrol\0 where 0 is the enum down. etc etc.

To control it all I have build a mobile webapp with JQuery mobile and loads of javascript:
Because the netduino isn't capable to host the mobile web-app(found out the hard way) I have bought a Raspberry Pi to host the web-app. Raspberry was pretty easy, put Debian on the sd card, get all the packages in with aptitude, set permissions and presto. All you have to do to make it work is modify the header in the apache config to allow cross domain call. Oh and set the Jquery setting ;)

So what's left to do now is make a power stabilizer to get the 12v car battery to 5v, for the transistor, ada fruits RGB led strip and to power the raspberry Pi. Then I have to make something to stabilize the car battery to 12v. The car jack and DIS igniter get their own private car battery cause they will be on the trailer and pull loads of amps. Im almost done coding, have to add some buttons and update the screen for the settings.
The devices are connected through a small Wifi AP

When I have it all done, its going to be in a lexaan box, with buttons etc. looking pretty in the field with all the LED's.

The team of idiots :) consist of a netwerk expert from Thales, Lotus dealer/race driver/shop manager, technical drawer/teamleader and me the software engineer/welder.

As you can read, the weakest part of the team is the fine electronics ;)

ps. we've been add this for many years and for example the gassifier is at version 2.5 already. The cannon and trailer are getting an overhaul too but all less drastic than last year because we don't have that much spare time left.

If it wasnt for this forum and all the wonderful tutorials wouldend have gotten so far in such a small amount of time, really great this community. When its all done ill post the code for others that need inspiration

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