run Sim900 from Xiomi 10000mAh Power bank

[SiddharthGajjar]

i have xiomi power bank of 10000mAh and it is capable of supplying 2A current.
and i want to operate SIM900A from it.

i have read the datasheet of SIM900A and it says that it will work fine in range of 3.4 to 4.8 V DC

i have tried the diode 1N4148 in series with that but it gives me garbage value.\

i also have tried lm317 but its open circuit voltage is 4.4V but when i connect SIM900A with that it reduces to 3.2V

Give me some regulator circuit design which not fluctuate.

 

[betwixt]

A little bit of electronics knowledge can be a dangerous thing!

Firstly, what voltage does the 'xiomi' power bank produce? The current rating is almost irrelevant, it's the voltage that matters. 'xiomi' is a brand name not a recognized specification.

The 1N4148 is rated to carry 0.2A before burning out so that wasn't a good choice of diode!

LM317 is also under current rated but with a suitably large resevoir capacitor could probably handle the average current needed by the SIM900A but it needs at least 1.5V more at it's input pin than it's output pin. So what voltage did you feed in to it and what value resistors did you use to set the output voltage and what value reservoir capacitor did you use?

Brian.

 

[Audioguru]

A "power bank" produces an output of 5V to charge a cell phone.
An LM317 with a 5V input and resistor values too high might produce an unloaded output of 4.4V because its resistors and its load must draw at least 5mA to prevent its output voltage from rising.

 

[SiddharthGajjar]

of course xiomi is a brand name but i am posting what actually i am implementing.
power bank is producing 5.05 volts and i am feeding it to LM317.

input capacitance i have placed is 1000uF/25V and same at the output side
i am using it without resistor network. so Adjust pin and output pins are short.

it gives me 4.45 output open circuit voltage. and 3.2 to 3.4 volt when i connect SIM900.

now i direct connect the power bank with SIM900 in series with 1N4007 diode it also gives me garbage values.

 

[srizbf]

as indicated by 'betwixt' already , the choice of diode is not correct for sim900.

have 1N5401(or 02) in series with your pwrbank and test.
no need for LM317.

 

[SiddharthGajjar]

i will try it with 1N5401.

but we will going to install it in open environment

will it be affect by the condition hot or cold environment?

will the cut-off voltage fluctuate?

if yes suggest me some filter circuit.