max 232 circuit

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ghostman11

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hi guys i have tried to use the search function on the site but for the last few days it dosnt seem to be working. so forgive me for asking but does anyone have a diagram for using a max 232 with a pic, showing the caps etc/
many thanks
 
ghostman11 said:
hi guys i have tried to use the search function on the site but for the last few days it dosnt seem to be working. so forgive me for asking but does anyone have a diagram for using a max 232 with a pic, showing the caps etc/
many thanks
Click to expand...
hi J,
This should help.

Eric
 

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hi J,
The way I read the d/s for the MAX231 is that it has no internal charge pump, so it it requires a 7.5 to 12V supply, as well as the 5V.

**broken link removed**
 
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i am not using a regulator eric (i rarely do) its just a straight 5v feed, i could i spose use a reg and 12v supply, while i go slap myself for careless buying
 
Don't beat yourself up too bad, there are a Bunch of flavors in that series.

I like Erics' take: a locally regulated +5 is more stable, and fed from a ~+9 does the 231. No sense orphaning $60+. Good Hunting... <<<)))
 
i thought the RS232 standard allowed +-5v input, if so there is a small chance of the max231's working on 5v. Its worth a try
 
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You could always use the PWM module of the pic to make a simple boost converter.

Mike.
 
The MAX231 is for external RS232 voltage references, i.e. no charge pump.

For a cheap pin compatible version of the MAX232 look up EXAR (SIPEX) 232 on Farnell, just over £1 each, and they work with 0.1uF caps!! Which I have a ton of.

I think what Mike was referring to was using the PWM of the PIC to boost the output voltage from 5v to 7.5-11V for your reference, my USB->232 levels sit at +/- 8.8V, my PC RS232 port sits at +/- 10.5V, such a wide range!

Look here: https://www.ladyada.net/library/diyboostcalc.html for some interesting reading!

The reason it the image shows 3 caps is because one is a filter cap, and there are 2 main caps on C1 + C2 that make the circuit work.

HTH
Wilksey
 
great to0 see you wilksey!! hope your well thanks for the info i will order some "propper chips "
thanks for the link pommie interesting stuff! give me plenty to read
 
Great to see you also Ghostman, hope you are doing well!

I think the 232 chip was one of the first things I ever hooked up to a PIC, you can get another variant of the chip with no need for external caps, they are very expensive though!
 
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