How to hookup a LE33
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I'm still learning on the electronics. So I have a question. I bought a couple of LE33 voltage regulators which finally arrived today. I want to use them to power my antenna's directly from a 5V power adapter. I have been looking on google for hours, but I can't find an example of how to connect them. The test circuit on the data sheet says that I have to use a 0.1 uf between VIN en GND, and a 2.2Uf between VOUT and GND.
But when I went to the local Electronics shop, the guy at the shop showed me a 2.2 uf which was really huge. About 2/3 the size of a Pro Mini. I asked if he couldn't order them any smaller. And he said that I would need an electro capacitor. Which is strange because the test circuit on the datasheets really shows the black rectangles.
Anyway do I need any capacitors? If so which ones and how the I connect them. It would be nice if someone could draw a simple circuit. Because I wasn't able to find it on the forum.
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The size of a capacitor will vary depending on the maximum voltage it supports. The 2.2uF cap is usually electrolytic (sometimes tantalum) while the 0.1uf ( = 100nF) is usually ceramic or polyester.
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@rvendrame Thank you very much for your reply. If I only connect a NRF24L01 to the power regulator, what is the capacity of the electrolytic capacitor I need to connect to the LE33? I'm not really sure if I understand this part correctly, but if I connect a 2.2 uF to the LE33 vOUT and the ground and also the 4.7 uF to the + of the Antenne and to the ground, than I should have a 6,9 uF capacitor. Or can I leave the 2.2 uF out of the circuit?
I'll only use the LE33 for hooking up an antenna to a 5V Pro Mini.
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You just need one cap in order to smooth the noise at radio , put it as close as possible to radio VCC/GND pins.
The value of 4.7uF is empiric AFAIK. You may need to play a bit with values to find the best cap for your situation. In fact, it depends a lot on your power source --- For example a batterie usually delivers clean power compared to a cheap phone charger.
You might not even need it... The typical symptoms of noisy power are from eventual transmission fails (st=fail on serial monitor) up to complete node frozen.
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There are a potentially a couple of (related) issues involved here, regarding caps.
Voltage regulator chips often specify input and output capacitors, partially to reduce the ripple, but also sometimes in order to keep the voltage regulator internal circuitry stable. For the latter purpose the regulator manufacturer often specifies capacitor size (perhaps a range). Sometimes they also specify how much resistance the capacitor should have, called ESR: Equivalent Series Resistance. This part is very much dependent on the specific regulator. (As has been noted, a capacitor also has a max voltage, which should be at least 50% higher than the voltages you expect the inputs and outputs to experience; higher voltage increases the size). These caps should be close to the regulator (to help keep it stable).
AND - we have found that it often helps to use a cap near the power leads of the nRF24L01+. There is no specified size tho. Larger ones help keep the voltage steady during spikes in the current used by the radio. Smaller ones help reduce high frequency oscillation. Sometimes people have used both! (One to smooth high frequencies, one for low frequencies).
It is quite possible that the output capacitor for your voltage regulator will also serve to stabilize the nRF24L01+, especially if it's close to the radio as well as the regulator. You may just have to test, and see how reliable the radio is.
Keep the wires to the radio short; if you cannot, the cap close to the radio becomes more important, even if you have one on the regulator output.
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@Zeph and @rvendrame thanx for claryfing things. I'll just have to build up a test circuit on a breadboard. I'll start with adding the 2.2 uf as specified in the datasheet and keep the radio wires short and will see from there. The specs of the LE33 are very promising, so I'm hoping to get this to work.
At the moment I've setup a lot of sensors on breadboards. The 4.7 uf cap is 20cm away from the radio, but no problems so far.
