buck regulator does not look too good

Hi,

I was trying to get a steady 3.3 V to run my nrf24l01+ pa lna so some people in this forum recommended me to buy a buck converter. I bought this one:

http://produto.mercadolivre.com.br/MLB-739508297-fonte-ajustavel-regulador-dc-dc-step-down-lm2596-arduino-_JM

I use 9v as IN and I measure with a multimeter and I get around 3.3V at the output after spinning the tripod to the right position.

Ok, so I connected my nrf24l01+ to this buck converter and it still does not work good, actually it works worse when compared to using the 3.3 V pin from arduino to power it.

Why? Even using this buck converter should I use decoupling capacitors on + and - of my nrf24l01?

Use a linear regulator for analog circuitry, not switch-mode. RF linear amplifier is analog circuitry.

The convertor is rated at 2A whereas the rf module uses very few microamps. Although not specified there is probably a minimum current that the convertor will tolerate. Considering how little current the rf module uses why not power it directly from the arduino 3.3 volts. Alternatively power it from a couple of AA cells which will power it for at least a year.

You want a good quality solid supply for the RF transmitter - power supply junk will just end up modulating the carrier otherwise. In particular although the transmit current is 11.5mA, you want a supply that is rated well above that so it doesn't hiccup when transmit mode switches on and off. SMPS's tend to hiccup on load changes more than linear regulators. Some of the on-board 3.3V supplies on some Arduino's are actually by-products of the FTDI serial USB chip, and not very solid, but modern Arduino's are probably capable or decent 3.3V rail.

I really need to use an external 3.3v cause the 3.3v pin from arduino is not too good. Could anyone take a look at this buck converter and check if it has good output capacitors? Cause usually I use a 10uF capacitor with a 0.1uF capacitor with my nrf24l01. Does this buck converter has a good capacitor?

Attach a photo/picture of your configuration, you guys do like put your foot in it sometimes.

Do you think ams1117 will be better than this buck converter? If I use ams1117, do you believe I will be using a better converter?

batata004:
Do you think ams1117 will be better than this buck converter? If I use ams1117, do you believe I will be using a better converter?

Yes, that should be better. It is a linear regulator.

The buck converter you were using will have a high output ripple at anything between 100 kHz and 300 kHz which will tend to modulate your RF signal and cause interference. While you could use it with adequate filtering it is much better to start with something with lower noise.

Russell.