Still waiting for an updated complete schematic, as requested in reply #12.
LM7809 circuit.
Move the 100ohm resistor to the input of the regulator, and make it <=10ohm.
No resistor in series with the output.
Add input and output caps to the LM7809. Values are in the datasheet.
Supply the Mega on the DC socket, not Vin.
The three 1n caps are almost useless. Proper decoupling of the LM7809 will replace them.
No motor cycle battery? Just a 33mF? (33000uF?) cap?
Supply could dip without a battery.
A diode + electrolytic buffer cap on the input of the LM7809 could fix that.
Leo..
no battery with the alternator i have, if i use the barrel jack i wouldn't need LM7809 then right? or am i powering it after this regulator into the barrel jack.
perkinja:
no battery with the alternator i have, if i use the barrel jack i wouldn't need LM7809 then right? or am i powering it after this regulator into the barrel jack.
The DC jack has an extra layer of protection because of the reverse protection diode between DC jack and Vin.
And it reduces heat in the Mega's onboard regulator with ~20%.
Circuit stays the same. Just inject 9volt into the DC jack instead of Vin.
An alternator without battery produces recitified AC. (DC with gaps).
An electrolytic cap (to bridge those gaps) is a must.
I would use a 10ohm resistor and a 1N4004 diode in series between ++motorbike and LM7809 input.
(the 10ohm resistor could be replaced with some sort of small lossy (resistance) inductor)
A 470-1000uF cap from 7809 input to 7809 ground (close to regulator), and a 10-47uF from 7809 output to 7809 ground (close to regulator).
Leo..
My enclosure for the arduino mega wont fit with a barrel jack connected plugged in, could i just unsolder it and solder the two connections there and it be safe? ill do what you advised and post back when i have some results, thanks leo.
Post the changed diagram before you start building.
Leo..
There should be current limiting resistors on the base of the transistors that drive the turn signals.
Updated schematic, I'll gather the parts tomorrow at school the cap values you listed should all be electrolytic caps i take it? I'll check back periodically tomorrow to make sure the schematic is correct etc.
Are you sure about the 33mF? That is 33,000uF and will be very big.
There should be some 0.1uF ceramic capacitors as well.
Looks like your decoupling circuits are a mess, especially around the regulator.
The input of the regulator seems ok.
A 470-1000uF buffer cap and a 10ohm resistor will filter/smooth any alternator hash and interruptions.
A 100n cap from the output of the 7809 to ground is probably enough (100n is also used in the datasheet). The mega already has a 47uF cap from Vin to ground.
Also add a 100n ceramic cap across the electrolytic input cap.
Remove the 100ohm resistor.
Leo..
Grumpy_Mike:
Are you sure about the 33mF? That is 33,000uF and will be very big.
There should be some 0.1uF ceramic capacitors as well.Looks like your decoupling circuits are a mess, especially around the regulator.
Well this is my first project so I never expected it to be perfect. I'm open to any and all methods of improvement as well as i try to get this to work.
I hear ya....
I'm having the same issues with my Arduino. Basically i'm measuring electric motor current, voltage, rpm of a PWM controlled brush motor, my Arduino restarts every 10 min or so.
Iv'e tried all the ideas above, nothing has worked.
Wawa:
The input of the regulator seems ok.
A 470-1000uF buffer cap and a 10ohm resistor will filter/smooth any alternator hash and interruptions.
A 100n cap from the output of the 7809 to ground is probably enough (100n is also used in the datasheet). The mega already has a 47uF cap from Vin to ground.
Also add a 100n ceramic cap across the electrolytic input cap.Remove the 100ohm resistor.
Leo..
So the 470-1000uf should be an electrolytic cap with a a 100nf ceramic cap across the positive end of the electrolytic cap. 10 ohm resister before all that and then a 100nf from output to ground.
I was planning on unsoldering the barrel jack and then soldering my output of the regulator to it so i have that protection diode. is this ok?
Image embedded for our convenience:
Technique described here.
Nobody's mentioned it yet, but you really should have a series diode on the 12 V rail, and TVS or zener (~20V) across GND & 12V. Those protect against spikes and reverse voltages. Here's a good discussion over on eevblog.
Cheers,
/dev
So the 470-1000uf should be an electrolytic cap
You have no choice about this, you can not get any other type of capacitor at this value.
a 100nf ceramic cap across the positive end of the electrolytic cap. 10 ohm resister before all that and then a 100nf from output to ground.
No, both the input and output cap on a regulator need to be 0.1uF ceramic, in addition to any large electrolytic you may have.
I was planning on unsoldering the barrel jack and then soldering my output of the regulator to it so i have that protection diode. is this ok?
Well the diode only protects against reverse voltage polarity so there is not much point in doing this.
Remove that 100R resistor from the regulator to Vin. What do you think it is doing?
Why are there three unattached 0.1uF capacitors shown close to the regulator.
You seem to be a bit mixed up about capacitor values
1nF is 10-9F
0.1uF is equal to 100nF or 10-7F
1uF is 10-6F
1000uF is equal to 1mF or 10-3F
You have 1KuF on the input to the regulator. A value of 1000uF is not called this.
You have a 10 to 47nF on the output of the regulator, this should be 10 to 47uF. As I said before BOTH must have a 0.1uF ceramic in parallel with them.
you really should have a series diode on the 12 V rail,
I would disagree with that. But agree with the rest of the last post.
Grumpy_Mike:
Remove that 100R resistor from the regulator to Vin. What do you think it is doing?
Why are there three unattached 0.1uF capacitors shown close to the regulator.
Well according to my knowledge, that's a rc low-pass filter, I made the circuit last night before i went to bed and forgot to connect them to the lm7809's output that powers the board.
No it is not a low pass filter circuit because the capacitor has to come after the resistor not before it.
Even if the circuit was correct the 100R resistor would give it a high output impedance, much too high for a power supply.
that is how it should be connected. Again i said i forgot to hook the 3 caps up last night before i posted that image but with them connected i'm fairly sure that is a low pass filter.
Look you are asking for advice and I am giving you the advice from my 50 years in electronics. That filter with those values are shit. Feel free to make a compleats mess of your project.
Did you actually read that last reply where I told you why it would be a very bad circuit?