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5. MAX 232 & 233


Two really easy circuits to build

The Max 233, is probably the easiest of the two and more reliable. If you're a bit of lazy Tw*t you can buy these circuits ready made. My favorite stockiest is Tailor Made Circuits and can be found at this address. or here


The following text and images were from



5a. MAX232


The voltage tolerance of the capacitor should not matter; anything over 12v should work fine.

Make sure you use electrolytic capacitors, & put them the correct way, as shown (White side is positive, black side is negative):


5b MAX233



Parts List

1 x MAX233 Microchip

1 x 9pin DB9 Female Serial Cable


Optional Parts

1 x 20 Pin Microchip holder (allows easy replacement of IC)

1 x 4 Pin internal PC Audio connector (Female)



5c How to Make a Simple Max 233


By Granty


Here is A List of Parts Needed: From Maplins


9-Way Snap Lock Hood KE94C

D-Range 9 Way Plug RK60Q


4 Core Cable………….


The above pic shows pin 1 where the dot is on the IC...ive colored this for this tut.




With this method we solder everything onto the IC & D plug

Without the need of pc board.

Good soldering skills are needed.



Turn the IC over so we solder the wires on the underneath


Legs to solder on max 233 IC are as follows;





9-6 Ground.


Pins to solder on the 9 pin D plug are:





Wires to solder from 9 pin D plug To Max 233 are:




5 - Is Ground and can connect to 9-6


Wires to solder onto IC that go to modem are:







The picture below shows Where the Wires Are Soldered onto i.c

And D plug...





Below is a picture of the IC with the soldered wires connected.



Picture of the 9 pin plug with pins bridged and soldered



Picture below shows the IC and plug soldered and in place inside the case.




Once done close the case making sure no wires are touching each...other…





Here Are Some Picture points To Connect for the Max 233 To Work…


First Image Is Ambit 250----255




Below Is the Pin Layout for the Ambit 200.And 120



Below Is a 5100




Below is A Picture off the Surfboard 4100


Below is A Picture of the Surfboard 4200



This tut is not for the fainthearted and for the sake of £12 +p&p

It would be wiser to purchase either the 232/233 from members on the forums...


But if you're like me who would rather burn your finger tips...give it a go…