Hello electrical friends, and greetings from Germeny.
Can anyone please help me to chosse the right capacitors for my project ?
I have added a shematic.
I forgot to mantion the operating voltage: AMS1117-3.3V
When you ask "which capacitor" do you mean a mfg and partnumber? Your schematic already has the type of capacitors defined.
http://www.advanced-monolithic.com/pdf/ds1117.pdf
22uf Solid tantalum - as the dtaa sheet says.
You have not shown what voltage will be applied at the jack input.
The
is a linear regulator with a 1.3 dropout voltage so you need at leats 3.3 +1.3V = 4.6V
Sorry, I meant the type of capacitors and the capacity.
I am not Sure if my shematic is correct. Because the dataseet of the AMS1117-3.3V says that a 22yF Tantalum capacitor.
The Jack Input is feeded with 6V 1A.
Tantalum capacitor are fine but are a little costly. I've been using a 10 microfarad (µF) ceramic on the input.
On the output I've actually purchased the Tantalum 22µF from AVX. For me building one maybe two boards the shipping costs more that the parts so I don't bother trying alternates to save a few €.
You could try a ceramic of maybe 2 to 10 µF and a 20µF aluminum. But I don't think its worth it.
BTW I'm using SMD parts. If you are using through hole you will find a lot of tantalum capacitors on ebay. The issue here is you might get some "old stock" that has not been stored properly. You can use a higher value tantalum if you find a good deal on them.
okay man, thanks. Is there a problem if I would use a higher capacity for example 100yF Tantalum other than the higher cost of it ?
Adding a 100nF ceramic capacitor next to the voltage regulator input pin is recommended even when you use a parallel 100uF tantalum.
If someone has an ESR meter and a 100uF & 22uF tant. capacitor can they measure their ESRs (no access to my meter right now).
Yes, if you make it too large, if the input gets shorted to ground while the capacitor has voltage it can flow back to the input and damage the regulator.
And @LarryD 's suggestion is right on. And he does mean "right next to the regulator pins".
Okay thanks man. In a German Topic, someone said, I should connect it like this:
100nF ceramik - 10yF Electrolyt - AMS1117 - 10yF Electrolyt - 100nF ceramik - ESP8266
Wow, never thought this could happen. Good to know. I wish I was an electrician.
That would likely work as well. I don't think the values are that critical, and the suggested values insure the device performs to their specification then transient input voltages and loads occur. For Arduino devices the transient response is not critical.
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