# Tagged Questions

196 views

### Charging a small 100uF 450V capacitor with a small battery?

How can I easily charge a 450V capacitor with a small battery such as a 1.5V or 9V while stepping the voltage up in between so as to provide a voltage near 450V for the capacitor? I'm looking to ...
107 views

### Very low power: Most power-efficient way of storing charge for hours

I'm researching the feasibility of doing an art project that involves soaking up ambient RF power in a city (energy harvesting) and then playing a 1 second sound clip through a speaker as soon as ...
322 views

### Using super capacitor alternative to battery as a backup power for laptops

I'm interested building my own battery pack using a series of super capacitor, something like this : http://youtu.be/z3x_kYq3mHM I plan to use it as a power backup solution for my laptop. Based on ...
255 views

### Is current able to flow through a Capacitor at DC? [duplicate]

Can someone clarify whether or not a capacitor blocks current at DC? simulate this circuit – Schematic created using CircuitLab
526 views

### What is this white stuff inside this circuit board?

I'm having problem getting any output from this universal adapter for my older laptop, so I opened it up to see this rubber-like white substance inside, on top of the big 68uF 400V capacitor. A ...
101 views

### Two questions about charge between capacitor plates

Let's say that we have capacitor with two identical plates - but one of them (let's call it plate A) is 50% of the size. Let's put a current through this capacitor so that there is some voltage V. ...
121 views

### The voltage of capacitor across battery never reaches battery voltage

I made some homemade vinegar batteries. The voltage of each cell was measured around 0.45V. I have 18 of them in series and I measured around 6.5V for the whole chain. Since the vinegar batteries ...
224 views

### Simple generator to light a series of LEDs question

Playing around with a simple circuit idea with friends but none of us have really worked with circuits since college so we need a little guidance. The thought is to have a small generator (someone ...
108 views

### what is the best way to charge a capacitor bank from an SLA battery

I need to charge a capacitor bank of 25 2.5v 55 farrad capacitors from a 2v 200Ah gel cell SLA battery, and modify the discharge time so that it discharges at 150Ah. I was wondering what the most ...
1k views

### Pulse-powering heavy loads with a coin cell

Lithium coin cells are rated for fairly low standard current draws, on the order of 1 to 5 mA. Also, while they allow greater pulsed current draws (i.e., periodic bursts), this appears to be ...
138 views

### Need chargeable momentary 15 watt regulated voltage source

I'm working on a RF telemetry side-project that requires an amplifier IC to be run for about 5 seconds bursts between charges. The system is portable and runs off of a 3.3V battery that can supply ...
433 views

### Using a high C capacitor

Let's say I've got a device which requires 700mA at 5V and I want to power it of a capacitor for one full hour. Now if I calculate the required capacity I get: C = I*t/V = 504 Farad. Capacitors like ...
584 views

### Charging 35V 470uf capacitor with coin cell

I want to charge a 50V 470uF capacitor up to 35V with the smallest battery possible. Can a coin cell do this 3000 times? Possibly a 2450 or 2477 coin cell? Also, can the capacitor be fully charged ...
2k views

### How long can a capacitor stay charged?

If I fully charge a 1.5V capacitor from 1.5V battery, how long can it keep the charge? If I connect it to 1.5V bulb would it lose that charge instantly? If yes why? Where would it go?
2k views

### Possible causes for AAA battery to explode

Today, the AAA battery in my remote control exploded. The "pop" sound is pretty loud. I've been using this remote control for years, and I'm more inclined to believe that it is the battery issue ...