# Tag Info

40

Consider an antenna that converts all the electrical energy from a power oscillator to an electromagnetic radio transmission. Let's say 1 watt is fed to the antenna and 1 watt is the emitted radio wave power. That power is flung out in most directions; just like a lightbulb emits light power in (virtually) all directions. The lightbulb isn't just a similar ...

19

Check out the SM74611 Smart Bypass Diode from Texas Instruments. Forward Voltage: Vf[V] = 26mV @ 8A, Tj = 25°C Other alternatives: LX2400 Cool bypass switch (CBS) from Microsemi Typical Forward Voltage VF = 50mV @ 10A, Tamb = 85°C SPV1001 Cool bypass switch (CBS) from STMicroelectronics Vf[V] = 120mV @ 8A, Tj = 25°C Vf[V] = 270mV @ 8A, Tj = ...

18

An ideal diode controller and MOSFET can be applied this situation -- the net effect is that of a Iload*Rds(on) voltage drop diode. Probably the simplest to apply would be Linear's LTC4412. Dedicated supercapacitor charger ICs also likely would solve the issue, but would require careful specification.

17

Back when I was in grade school I had a crystal radio set. A crystal radio contains no amplifier. The output signal is completely powered by what is picked up from the antenna. I had around a 50 foot length of wire running out my bedroom window to a shed in the back yard as a antenna. With that I could pick up a 50 kW AM station over 20 miles away quite ...

14

Understanding power will be key to this project. In electrical circuits power, voltage and current are related by the equation $P = VI$ or, if we know the resistance, $P = \frac {V^2}{R}$ or $P = I^2R$. You have a voltage reading but you have taken this with no load resistor so you don't know what current will be supplied when you add a load. ...

9

~ People are making vibration coupling backpack type units that produce in the few Watts range. ~ A typical Chinese squeeze light when operated frenetically will give about 1 Watt. After 5 minutes of use at that level your hand drops off or feels like it has. ~ A properly build hand squeeze power unit could make more like 5 Watts at the same level of ...

9

The system will work. How much rubbish you can compact how many times depends on How much sun the panel gets. How big the panels are (Watts peak power in full sun) What technology they use (crystalline silicon, amorphous silicon, CdTe, ...) - And energy required for trash compaction (bin volume, rubbish type, rubbish volume) Added long after: Big ...

8

To answer the question, it's called energy harvesting because in most systems the rate of collection (input power) is very different from the rate of use (output power). Most such systems run intermittently, so a key parameter is how much energy the the application consumes each time it runs (output power times run time). This then determines how often the ...

8

Standard cassette tape adapters have no active circuitry. The audio signal is simply wired directly to the tape head, like this... Your image shows an adapter which has been hacked to include the circuit from a Bluetooth stereo headset. It is described here... How to Hack Your Car's Cassette Deck into a Wireless Bluetooth Music Player There is no ...

7

If you add few turns of wire to your antenna coil probably will get higher voltages and lower currents so you could employ Schottky diodes. Impedance matching is very important in harvesting RF energy. Some ferrite core could also help because will capture more energy. Energy required to switch a synchronous Mosfet rectifier at 13 MHz is probably more than ...

7

I have an outdoor sensor (which will have to work in the winter on Poland, however, we usually have temperature much over -10 Celsius degrees) which needs 5V. The sensor operates 24 hours per day and consumes about 300 mA when working, for about 10 seconds every 5 minutes and less than 1 mA the rest of the time. Energy required: Operate: 10s in 5 ...

6

Don't let this happen to you: Batteries don't like excessive voltage or current and will destroy themselves and injure others if proper steps are not taken to ensure these conditions do not occur. For these reasons it is very important that the charger you use is suitable to the battery. Remember, Battery acid can blind or disable you. Electricity can ...

6

If we generalize your question a bit to cover not just RF energy harvesting, but electromagnetic energy harvesting in general, we do that all the time. The sun is essentially an electromagnetic transmitter with a power output of approximately 4 × 1026 watts. A very large solar farm has a (peak) output of 6 × 108 watts. To put this in perspective, if you ...

6

The TEG sees as its load the voltage across Cin. If Cin is large enough to reduce the switching effect of the boost converter to a small ripple, then there is simply a steady(ish) current flowing through Rteg to the steady(ish) voltage on Cin. That is resistive. The boost converter should then contrive to draw (on average) this current out of this voltage ...

6

Wrong assumptions and interpretation of datasheet specs. SHDN Threshold Voltage 0.4 Vmin, 0.6 Vtyp, 1 Vmax This means it switches On OR Off at some threshold of 0.6V with a worst case tolerance of +0.4/-0.2V. ( Disabled active low or negative logic) When they define a logic level, for safety margin from noise they define a "1" above some level and ...

5

Let me make a life a little easier with a simplification of your hard to read circuit: - The simplification is getting rid of 50% of the changeover switches. What can you use for these switches? I would consider using N-channel MOSFETs; two per switch element. You will need a supervisory circuit that of course needs to be very lower power but I don't see ...

5

If your circuit is mainly as described with no electronics in the middle then you definitely need a diode. What you then have is effectively an alternator with diode rectification. Voltage generated needs to be greater than battery voltage + a diode drop. If your system applies a magnetic pulse to the coil and then removes the field rapidly you may be able ...

5

That won't work, you can't generate the needed power to light a lamp that way. It works for the watch because that uses about 100 000 times less power than the bicycle light. What's wrong with your dynamo? If the problem is that you have to peddle harder, then the sideways motion to electrical power conversion doesn't help. There's the Law, more ...

5

A MOSFET is better than any diode and it can be used if there is enough DC voltage to drive the gate. At low currents this MOSFET would be cheap and small. If you dont have suitable gate voltage then there are other options: A Germanium diode will drop less than the Si Schottky. A Ge Schottky would, in theory, be even better but I have not seen such ...

5

First off, Würth's datasheet is fine and perfectly complete. It doesn't list primary and secondary windings because those are totally arbitrary. You happen to be using the low inductance winding as primary, but someone else might want to use the high inductance winding as primary. They expect you to know which winding you want to use for what purpose. ...

5

I need to amplify a weak signal(few nanovlts) from solenoid to few hundred millivolts. You are chasing at shadows. There is probably no signal there at all. Nanovolts (10-9 V) are ridiculously small units. There are numerous sources of experimental error which can produce voltages in even the µV range, including: Thermal noise. Current induced in your ...

5

You must use a 10:1 scope probe which is typ. 9 pf //10M which should never bother a good clock design. But in your case it may slow down the clock from load capacitance. Some Ring Osc uses string of inverters in a loop each with <1pF so putting a 9pF probe on the output adds latency from current limit. dV/dt=Ic/C simulate this circuit – Schematic ...

4

I don't understand the "one piece" requirement, but what you need is a motor. Electric motors have the great power of being capable of converting mechanical (rotational) energy in electricity and vice versa, and with a quite high efficiency. But if you need to take the energy from a "linear" movement, like from the surface of a tire, you need a gear which ...

4

Mechanical Generation of Power is basically how we first got electricity. It's a fairly common application, and there are over a billion of them running around outside. Automobiles have been using rotating shafts to power themselves since the very start. The schematic for it is fairly simple. An Alternator going into a rectification stage which is then ...

4

The Joule Thief mentioned in another answer is an excellent way to harvest the dregs of battery power. However, if surface mount components are not a problem, one can do slightly better. Look for ultra low power energy harvesting boost converters from Linear Technologies, Texas Instruments and perhaps other manufacturers. For instance, the TI BQ25504 can ...

4

I think you'd be hard pressed to get the required 150mW or so, although it isn't impossible. Looking into piezo-based energy harvesting systems, one product claims about 7mW constant power. I would assume this scales reasonable well though. This is using a 3x7cm bendable piezo element and some electronics to store and convert the energy. There's a lot of ...

4

You could easily provide far more useful information than you have. If you are serious about getting good answers you can help yourself by giving as complete and accurate a description of the environment as possible subject to secrecy constraints. If secrecy is not an issue then tell us what you are doing. In the comments you say "5 to 10 meters" but ...

4

Normally, like you say, the little bit of energy saving isn't worth the complexity. But yes, this can be done. In fact, this is the basis for how boost converter and flyback power supplies work. In those cases it is done deliberately to get power at a different voltage/current tradeoff than the input power.

4

It's certainly possible - one of the energy monitoring sensor companies one of our clients uses has clip-on smart meter sensors which harvest energy from the circuit they monitor to power sensors. There's a minimum current that they can sense, below which they don't harvest enough power to talk to the base station. I don't know off hand what a standard ...

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