How to use NPN transistor as a current amplifier?

Other Hardware General Electronics
1

Board: Arduino MEGA 2560 Rev3
IDE: Arduino 1.8.10
OS: Windows 10
Additional unique hardware involved: EPROM M27C256B-12F1

Link to hardware:

I'm new to electronics and attempted to find the information I'm looking for via google searches at youtube videos, but none of the explanations I've found are low level enough that I understand. I'm hoping someone here can help me or link me to someplace that can do so.

I'm looking to boost my Arduino MEGA256's digital pin current from 20 mA to 30 mA for reading a chip I was given and my research tells me that I should use a transistor to amplify the current. However, I cannot find any concise, easy to digest information for how to determine/calculate the type of transistor to use and the type of resistor to use with the base. Any explanations or links are very appreciated.

2

There are two ways BJTs (thats NPN and PNP junction transistors) are used to increase current:

  1. Active mode analog amplification. This uses transistor-action, and the increase in current is given by the transistors current gain or "beta" or hfe parameter.

  2. Switching mode - here the transistor is either cutoff or in saturation. The current gain is about 5 to 20 at most in saturation, no "transistor action" takes place as the base-collector junction is forward biased in saturation.

But before going further please give full details of all the hardware you've alluded to, and state clearly what you are trying to achieve.

3

@liminal

Could you take a few moments to Learn How To Use The Forum.
It will help you get the best out of the forum in the future.

Posting tips.

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4

@MarkT

I have an Arduino MEGA 256 Rev3 and am attempting to read whatever data is contained on an EPROM with the model number M27C256B-12F1.

The data sheet and general specs can be found for it here:

I suspect that it is mostly corrupted gibberish, but I just want to be able to do it for the sake of itself, as the learning opportunity is really interesting. I've only previously made temperature controlled hotplates and photosensitive + switch activated LED stuff, so this is very new to me.

I know that the EPROM cannot be written to as it needs a UV light and nearly 13v to do so, but only 6.25v for reading which is something I can work with. However, the 30 mA it needs for reading is more than the Arduino MEGA 2560 Rev3 is intended to safely put out, and while I know it has a maximum of 40 mA, I also know you arent supposed to approach that if you can help it as it could damage the board.

5

liminal:
However, the 30 mA it needs for reading is more than the Arduino MEGA 2560 Rev3 is intended to safely put out, and while I know it has a maximum of 40 mA...

You're confusing pin/signal/data currents with power supply current of the chip.

Pin currents to read the chip is near zero.
It only needs ~30mA supply current, from the Mega's 5volt pin.
The Mega can supply about 400mA from that 5volt pin when on USB power.
Leo..

6

If I remember correctly, the 27C' is a fully
CMOS chip, so the address pins can be
connected directly to the arduino pins.
Herb

7

Like they said, and its a 5V component, not 6.25V, for reading.

It draws from its supply rails 1mA in standby, 30mA when reading at a 5MHz rate, the current draw depends on the frequency of memory access I believe.