How to change the SIM card with iron?

Question

Electronics

Hello
Tell me, there is a module for several SIM cards. There is a SIM900 modem
All SIM cards are connected in parallel, all VCC are cut off and the BC327 transistor is in the gap, which are controlled by an external module.
The problem is that the SIM card falls off when receiving a large SMS. And the modem itself has enough power, it is the SIM card that cuts off.
I read the documentation on SIM cards, it is written that the maximum current consumption is 400mA, and the transistor is designed for 800mA max.
I don’t understand what could be the matter =\ Maybe I don’t switch between them correctly at all?

Answer 1

It is believed that a fairly decent voltage drops on a bipolar transistor at the collector-emitter junction if a current of 400mA flows there. Do not want to try to change the transistor to a field-effect transistor or, in general, to an opto-relay with an assembly on field-effect transistors at the output? In any case, your drain-source resistance will be in the range of 0.1-5 ohms, which is much better.

Answer 2

With an oscilloscope, look at the power of the SIM card while receiving SMS.

Answer 3

Levenshtein is one of the slowest algorithms. Try another.
In general, look for bottlenecks. Take timestamps on different lines and see where and how much time the script spends the most.

Answer 4

1. Arrange alphabetically the database itself.
2. Create an index file similar to the book's glossary (alphabetical-ordered unique words from the entire text of the database file) with links to the required line(s) in the database file.