Max Voltage?

Megajolt Kit assembly Question and Answers. Be sure to review the <a href="http://www.autosportlabs.net/MJLJ_V4_kit_assembly_guide">Kit assembly guide</a>

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Jax2A
Posts: 2
Joined: Thu Nov 11, 2004 11:05 am

Max Voltage?

Post by Jax2A »

I'm working on using my Axim x50v palm to communicate with the MJLJ. The RX pin on the Axim is listed as 3.3v-5v. What is the max voltage the MJLJ can send via the serial port. Any ideas?

Jax2A
Jax2A

PioneerX
Posts: 1
Joined: Tue Nov 16, 2004 3:16 pm

MAX232 Voltage

Post by PioneerX »

Jax2A,

The MJLJ send serial data via the MAX232 chip. According to the data sheet on this chip it is designed to produce a data stream using a typical value of +/-8v. Basically the chip takes to 5v supply and uses the capacitors to double it to 10v then inverts it to get +10v & -10V this is used to create the signal on the serial port. so without a load attached (resistance) the volage would swing from +10v to -10v, however the typical value is +8v & -8v when load is attached (ie a computer). It does state that the worst case would be +/-5v, but this is only achieved if the +/10v is also being used to power other devises at the same time (not the case in MJLJ). So I would suggest that you will need something to lower the 8v signal to below 5v.

Regards

Simon

PS. The datasheet can be found @ http://pdfserv.maxim-ic.com/en/ds/MAX220-MAX249.pdf

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