Tagged Questions

4
votes
1answer
65 views

Substition of electrolytic capacitors in surface mount applications

I understand there are advantages and disadvantages against using electrolytic capacitors over others, such as ceramic, but from what I understand the main reason of choosing electrolytic caps is ...
3
votes
1answer
73 views

Is this a polarised capacitor

So I went to a local electronics retailer, Communica in Cape Town yesterday. I had a small shopping list including: 10x 10µF Ceramic Capacitor 10x 0.1µF Ceramic Capacitor The vendor didn't have ...
0
votes
2answers
99 views

What formulas do I need to use to design a voltage regulator circuit for a zigbee radio?

I've written the code for my zigbee radios, but now I face the obstacle of getting them onto a carrier board to allow access to VCC, GND, TX, RX via a 4 wire connector. The supply voltage is 3.712 ...
7
votes
1answer
239 views

Best place to place a decoupling capacitor

See this image which gives four options to place decoupling capacitors: (from http://www.learnemc.com/tutorials/Decoupling/decoupling01.html) I would say option (d) isn't good - I would recommend ...
23
votes
5answers
1k views

What's the use of a decoupling capacitor near a reservoir capacitor?

I've seen some circuits where a decoupling capacitor is used as well as a reservoir capacitor, like this (C4 and C5): I've read about decoupling capacitors and for me it looks as if they are meant ...
1
vote
3answers
167 views

Which connection(s) to a decoupling capacitor should be shortest?

Circuit Cellar-Issue 210- has this question "Which connection(s) to a decoupling capacitor should be shortest?why?" in its "Test your EQ section". I couldn't understand what they meant 'Which ...
20
votes
3answers
4k views

Can I replace all electrolytic capacitors with ceramic ones?

I am designing the power supply circuit for a system that needs several supplies, my questions are: Is it possible to replace all electrolytic caps (Mostly 100uF) by ceramic ones? What are the ...
3
votes
3answers
737 views

How much capacitance do I need in the input of LM78L05

I want to use LM78L05 as a fixed output voltage regulator as shown in the datasheet, as I cited below. My regulator is 2 meters away from the power supply filter. My input voltage is 24V, however this ...
3
votes
1answer
1k views

Why do we need 100nF cap in the output of an SMPS?

I was looking at Micrel AN-53 and I have noticed that in a circuit in the first page (circuit is below), at the output of an 400KHz, 27V, 7A, 180W boost converter, there are two 680 uF, two 10 uF and ...
8
votes
2answers
2k views

Why connect capacitors to motor body?

So I've found a motor circuit which looks like this: Since many users here believe that my hand-drawn circuit schematics are in fact pictures of flying spaghetti monster, I'll also provide a ...
4
votes
3answers
590 views

HUGE capacitor recommended in datasheet for Audio Amp

I'm using the TPA3111 audio amplifier in a circuit of mine and I'm working on adding the appropriate capacitors. However, on page 18/19 of the datasheet TI recommends to use a 220mF capacitor on the ...
1
vote
2answers
1k views

Circuit Design to Power the ADH8066 GSM Module

I am struggling to find the proper circuit design layout to properly power the ADH8066 GSM module and communicate with my Arduino. The ADH8066 requires a 4V power supply and can have a brief spike of ...
5
votes
3answers
1k views

How do I know where I need decoupling capacitors?

I'm building a motor driver shield for the Arduino. Here's the schematics (please forgive the messy layout): And here's the PCB layout: I'm testing it out by breadboarding it while running a ...
7
votes
1answer
433 views

Characterization of bypass capacitors

I was reading through a few post including Decoupling caps as well as this app note Xilinx Power Distribution Network. I have a question regarding capacitor values within a power distribution system. ...
7
votes
3answers
747 views

Sizing an RC snubber

My fridge is sending bad clacks to my loudspeakers when it turns on/off, I fear for the tweeters. I'd add a snubber/suppressor to the compressor but my notions about RC filters from school are 15 ...
5
votes
2answers
896 views

Cap's on H-Bridge… Seem a bit redundant?

The Below is a H-Bridge Schematic from this site: http://www.societyofrobots.com/schematics_h-bridgedes.shtml. Wouldn't the 10-100nF cap be rendered useless by the 10000 uf cap? Wouldn't the caps just ...
44
votes
11answers
34k views

What is a decoupling capacitor and how do I know if I need one?

What is a decoupling capacitor (or smoothing capacitor as referred to in the link below)? How do I know if I need one and if so, what size and where it needs to go? This question mentions many ...
17
votes
6answers
4k views

Decoupling capacitors: what size and how many?

Lots of chips nowadays require smoothing capacitors between VCC and GND for proper function. Given that my projects run at all sorts of different voltage and current levels, I was wondering if anyone ...