Junebug help??

[be80be]

Mrdeb The way you have that for the car you run the chance that the pic can be powered from the amp and that wouldn't be good. You could use this regulator bd3931fp for the pic **broken link removed**
You for sure want to use a capacitor on pin 3 of the lm386 For dc decoupling And you need the pic to turn it on when triggered. Use a Fet

 

[MrDEB]

my bad

the schematic for the car should have the transistor to turn it on and off.
the regulator is supposed to be a 12v unit w/ a second regulator or the zener/transistor circuit I posted earlier.
cap on pin 3?? first I herd any mention of adding a cap?
in sewries or parallel with the 10k resistor??

 

[MrDEB]

proposed changes

not real sure about cap on pin 3 or the zener / transistor section.
this schematic for automotive

 

[3v0]

Make sure that LM2937 is a part you can get. Check the ordering information on the part sheet. The last 2 digits of the number indicate the voltage with 33=3.3V, 50=5.0V, and 12=1V. I did not see where Mouser had any 12V version in quanties less then 4000.

Still suggest for 18 cents you can put a 5V LM2931 in place of the zener and related parts.

 

[MrDEB]

the NCV8674 output voltage?

data sheet says it will do for 5v or 12v but how does one set it for 12v??fixed
the LM2931 looks like a go at .21 from Mouser

 

[3v0]

data sheet says it will do for 5v or 12v but how does one set it for 12v??fixed

Yes they are fixed output voltage regulators as per the datasheet and my last post. One part with a 12 volt output is TS2937CZ12. Notice the 12 in the last two positions. It looks like you can not get them. I provided a link to a 12V regulator earlier.

the LM2931 looks like a go at .21 from Mouser

or .18 if you buy 25 of them.

 

[MrDEB]

Egadds batman I'm an idiot

I had another PIC go poof!
looked and studied my schematic and see I had the batteries wrong.had them backwards in the schematic. Don't know how I missed it??
I changed the schematic and then it hit me = I have 9v going to the PIC!!!
I measured the voltage at pin 14 to ground =4.5v
pin 6 to ground on the LM386=9v
insert PIC, activate the PIR then POOF

BUT looking at the schematic I have a ground loop so to speak that puts 9v to the PIC
it pays to take several looks at ones schematic.
On the home units I only have 4.5v
on the automotive units I pan on using the LM386 and 12v.
going to run 2 separate grounds ???

 

[be80be]

I no you have read this

• LM386 Battery operation
• Minimum external parts
• Wide supply voltage range: 4V-12V or 5V-18V
• Low quiescent current drain: 4mA
• Voltage gains from 20 to 200
• Ground referenced input
• Self-centering output quiescent voltage
• Low distortion: 0.2% (AV = 20, VS = 6V, RL = 8Ohm, PO = 125mW, f = 1kHz)
• Available in 8 pin MSOP package

I'm sure its going to cry with 14.5 volts going to it in a car. And i'm sure your not going to leave it on when the car is parked. You no what would happen if you put that in a car
and have no current limiting on it and hooked it up wrong A fire.

 

[be80be]

Not all LM2931 are a like if you want variable voltage you need a LM2931CT Here MrDeb I cleaned this up for you and posted the ExpressSCH files so you can make your PCB

 

[MrDEB]

Thanks but why adjustable??

the part I am looking at is
LM2931AZ5
this is the 5v unit.
the 12v unit is ncv8674 - harder to find unit
https://www.electro-tech-online.com/custompdfs/2009/05/NCV8674-DPDF.pdf
I need to check Newark again
Linear Regulators | Newark.com
plan is to connect to the ignition circuit or cigrett lighter w/ i-line fuse
the 12v reg for amp and 5v reg for PIC circuit

 

[MrDEB]

nice drawing of entire circuit

problem I have is the snap to grid feature.
set to high = 2 I need to move parts under snap disable.
QUESTION?? why the FET on the amp??

 

[ericgibbs]

problem I have is the snap to grid feature.
set to high = 2 I need to move parts under snap disable.
QUESTION?? why the FET on the amp??

hi,
Ref the express dwg program.

To nudge a 'component' SELECT it, press the 'Ctrl' key and hold it down, use the Cursor 'arrow' keys to move the component.

 

[MrDEB]

thanks didn't know that

will give it a try.
found the 2 voltage regulators.
Something very important that I / we forgot = the regulator needs about 2volts higher than what is needed
I picked a 5 v and a 10v regulator over at Newark
NATIONAL SEMICONDUCTOR|LM2937ES-10/NOPB|Linear Voltage Regulator IC | Newark.com
NATIONAL SEMICONDUCTOR|LM2937IMP-5.0NOPB|Linear Voltage Regulator IC | Newark.com
I think these are what I am needing??

 

[be80be]

The fet use less power but you can change it to npn. You ask

data sheet says it will do for 5v or 12v but how does one set it for 12v??fixed
the LM2931 looks like a go at .21 from Mouser

Take a look here https://www.alliedelec.com/Search/SearchResults.aspx?N=0&Ntk=Primary&Ntt=lm2931 for voltage regulators

 

[3v0]

The sentence I high lighted is not quite true. The additional voltage is know as the drop out. A low drop out regulator needs less additional voltage. Check the data sheet to see what the drop out voltage is and add it to the regulated output voltage to get the needed input voltage.

The LM2937 has a drop out of 1/2 volt so you could easily use the 12V version because cars regulate to 14V when running. The additional 2V might make the sound louder.

will give it a try.
found the 2 voltage regulators.
Something very important that I / we forgot = the regulator needs about 2volts higher than what is needed
I picked a 5 v and a 10v regulator over at Newark
NATIONAL SEMICONDUCTOR|LM2937ES-10/NOPB|Linear Voltage Regulator IC | Newark.com
NATIONAL SEMICONDUCTOR|LM2937IMP-5.0NOPB|Linear Voltage Regulator IC | Newark.com
I think these are what I am needing??

 

[be80be]

MrDeb if your going to use

cigrett lighter w/ i-line fuse

You would be better off using this regulator MC34063AP1G it's 50 cents or less and if you really get to making a lot of these it way less and the MC34063AP1G is used in almost every car adapter made

 

[MrDEB]

Will look at the regulators again

the FET uses less power but this is an automotive application so current draw is not a real concern BUT using something for the battery power unit might prove useful but the price of ?? vers how much will it save in battery power??
suggestions on which FET to use as I have not had any experience with FET's.
no resistor on pin 18 to the input pin 3 of the LM386? just a cap??
wish there was a way to turn unit on at say any speed over 25mph.
something extra??

 

[be80be]

You can change the fet but they just cost 4 cents if you by a 100 It would be easy to have it come on a 25mph

 

[MrDEB]

now Im curious???

why a different regulator??
and
how to make it come on at 25mph. thinking a hall effect switch or ?? on a wheel or ??
I was thinking a hall effect or IR/detector w/ fan in a tube.
just more "candy" but makes for a better product.
any suggestions on the FET??

 

[be80be]

It's 2n7000 should work good. Fan and tube is cool but hard to put on a car I just thought you may want to look at that regulator seeing it's in about every car adapter.
and you could make a good one for this cheap. when I get more time I'll post some thing showing it. You should just make one deer what ever you call it and make two
types of power supply's one for car and one for home like a modular sys. That way you can fix it so it can't be powered wrong and you could ship what people want with
out have to make two boards.