# Need some help getting started(simple stuff for a car)

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#### VooDooCC

##### New Member
I should be getting a different truck on Monday, but it's missing a few things I got used to. These are a compass, thermometer, and clock. I'm only going to do one at a time to stay semi-organized. So, starting with the compass: Digital Compass - Navigation PC Board pg.1
2 issues:
1) I need to figure out a way to drop from the battery (11-15) to 5V, I believe the best way would be a buck converter, but I've never built one and not sure where to start.

2) I would like to go from the 4 LEDs to 2 15 segment displays that would give a directional readout.

#### deansmith

##### New Member
have a look at the data sheet for 7805 . It looks like thats whats on the PCB. Its a voltage regulator (input 5 to 18 volts) output a stable 5volt supply. which means you can connect it directly to a 12volt battery without making any changes to the circuit. I cant think of a quick fix to change to 2, 15 segment displays. One solution would be to use the 1490 device with a micro controller. The schemetic and program would be very simple. Even if you have no experience with pics, im sure there are enough people here that would draw something up for you. Ive been looking for a device like yours to make a tilt sensor car alarm.

#### deansmith

##### New Member
ahhh.. after spotting the last word on your attachment (NEXT PAGE) i see that you can add a controller. The 16f628 is much cheaper than the f84 and has an internal oscillator. Hope that helps and i havnt just told you everything you already know.

#### VooDooCC

##### New Member
Stupid question, but what does the oscillator get me?

I have zero experience with PICs and don't even know what I'd need as far as programming, but I wouldn't mind learning about them,

#### VooDooCC

##### New Member
Electronworks, that looks like it would be great and will definitely keep it in mind, but I live in U.S.

Also, I dug a bit deeper into my electronics stash and found a few altera max 7000 DeVry eSOC development boards. I emailed altera and am waiting to hear back from them about a datasheet or schematic in hopes that I can use those and simplify everything a lot. I haven't used that board in about 5 years, so I'm not real familiar with it anymore, but I do know it uses a wall to 9V adapter and from that plug it goes through a 7805 with a decent size heat sink, so will I be able to just snip the plug off the adapter and splice that into the car or do I need something to drop from 12 to 9 and then use the adapter plug?

edit: if you do a google image search for "DeVry eSOC" the second one is the board that I have, unfortunately, the page doesn't exist on DeVry's site anymore so no info there.

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#### deansmith

##### New Member
Electronworks, that looks like it would be great and will definitely keep it in mind, but I live in U.S.

Also, I dug a bit deeper into my electronics stash and found a few altera max 7000 DeVry eSOC development boards. I emailed altera and am waiting to hear back from them about a datasheet or schematic in hopes that I can use those and simplify everything a lot. I haven't used that board in about 5 years, so I'm not real familiar with it anymore, but I do know it uses a wall to 9V adapter and from that plug it goes through a 7805 with a decent size heat sink, so will I be able to just snip the plug off the adapter and splice that into the car or do I need something to drop from 12 to 9 and then use the adapter plug?

edit: if you do a google image search for "DeVry eSOC" the second one is the board that I have, unfortunately, the page doesn't exist on DeVry's site anymore so no info there.
data sheet shows that the input voltage of a 7805 is up to 18 volts. the more amps you push through it, the warmer the 7805 will be. When the maximum temperature is reached. The 7805 will start to fry. I think you can push up to 1 Amp though the 7805. Check the type you have with the data sheet and add up what your circuit needs. ie 1 LED 20mA 2 LEDs 40mA and so on.

#### deansmith

##### New Member
The oscillator is a frequence which occurs every 4Mhz. 1/F( Frequency) =T(time). basically controls the speed of the code being executed.. like from the wall 50Hz would mean that the pulse to a light buld would cause the bulb to blink 50 times every second. 1 pulse every 20 ms. so fast that the human eye cant see it. It doesnt matter if your pic runs at 4 MHz or 2MHz. The 16f628 runs upto 4 MHz. as standard configuration.

#### deansmith

##### New Member
The 16f628 has a built in oscillator, so you save on components(4MHz quarz and 2 ceramic condensators.) 16f628 approx $2.50. 16f84 approx$4.50+ quarz+2ceramic condensators= more money and more hassle. Question was a bit unclear, so the answer might also be a bit unclear. Hope it helped.

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