0 down vote favorite  I needed some basic advice about impedance matching. I have an RF amplifier with 50 ohm output impedance, capable of generating 400W output power at 500kHz. I am trying to deliver this to a 12 ohm load.  I looked online and figured out that I need to match the impedance of the amplifier to the load. My question is what is the best way to achieve this? Would it be possible to simply use a capacitor and inductor and put an L section to the output of the amplifier? I saw that online stores have very cheap capacitor and inductors that is rated for very high voltages.  If that is not going to work is it possible to buy any transformers that would do that? For instance I saw that there are many cheap 220v-110v voltage converters, which should have 2:1 coil ratio. So in theory that should convert 50 ohm to 12.5 ohm and matches to my load. Will these work at 500 kHz as required for my application? Or are there other type of transformers that I can use for this purpose (there are many many types of transformers and I got confused which ones are suitable for impedance matching)?  Thanks a lot for the help.
120583
I needed some basic advice about impedance matching. I have an RF amplifier with 50 ohm output impedance, capable of generating 400W output power at 500kHz. I am trying to deliver this to a 12 ohm load.  I looked online and figured out that I need to match the impedance of the amplifier to the load. What is the best way to achieve this? Would it be possible to simply use a capacitor and inductor and put an L section to the output of the amplifier? I saw that online stores have very cheap capacitor and inductors that are rated for very high voltages.  If that is not going to work, is it possible to buy any transformers that would do that? For instance I saw that there are many cheap 220V-110V voltage converters, which should have 2:1 coil ratio. So in theory that should convert 50 ohm to 12.5 ohm and matches to my load. Will these work at 500 kHz as required for my application? Or are there other type of transformers that I can use for this purpose (there are many many types of transformers and I got confused which ones are suitable for impedance matching)?
60111
I want to transfer electical power wirelessly from a transmitter to a receiver coil.   Input energy is provided by a single phase step-down transformer - 230V/12V AC, 50 Hz, 1,000 mA.   Using the 12 V AC output I want to transfer as much of the available power wirelessly from transmitter coil to the receiver coil over a distance of 5mm.  How can that be done ? What calculations should i solve so as to achieve this ?  I want to transmit across 5 millimeters. The radii of the transmitter and receiver coils I am currently using are are 5cm and 2cm respectively  After transmitting it to the receiver coil, I wish to rectify and filter it and then regulate it to 5V DC use it to charge a battery.   I want 5V DC at the end of the circuit, but how can I accomplish that ?  What calculations and equipment specifications do I have to use so that I can figure this out?
29935
I have a project that needs a different voltage (or multiple voltages) than what I have available. Sometimes I need DC instead of AC, or I need a lower or higher voltage. How do I convert from one to another? Should I use resistors or a regulator or something else?  I've heard of converters, transformers, regulators, inverters, step-down, step-up, buck, boost, switching, linear, and other terms. Or acronyms (initialisms) like PMIC and LDO. Can someone shed some light on all this?
38356
I just started learning about electronics and decided to quickly sketch a circuit. When it comes to OP and changing the said circuit into an Ac equivalent, I got stuck. Sorry in advance if this is considered a basic question.
96938
i recently assigned for the Powerline Communication project for transmission up to 200MBps.the problem occurred when trying to find circuit for coupling between the modem and the powerline cable.is it just connecting the X2 class capacitor?or is there any special linear transformer for coupling purposes?  thanks....
121668
I have used the above simple circuit for a constant source where \$V_{\text{in}} = -5\$V, \$R_{\text{in}} = 390\Omega\$, \$R_f\$ is the load which ranges from \$110\$ to \$170\Omega\$....would using this circuit for a constant current source for the load be recommended?  As current $$i = -\frac{V_{\text{in}}}{R_{\text{in}}}$$ $$V_{\text{out}} = -V_{\text{in}}\frac{Rf}{R_{\text{in}}}$$ so it should serve as a constant current source, but while browsing the Internet for a constant current source I typically found these sorts of circuits:        Is there a compulsion to include the transistor in my circuit? If yes, why wouldn't my circuit serve the purpose for producing a constant current?
104185
EDIT:  Please read the whole post before automatically down voting. I KNOW the diagram is crap.  That is what I am asking about.  It isn't my diagram.  Original post:  I Web searched a bit and searched this site, but I didn't really see a good answer.  I thought line level voltage was insufficient to switch a transistor and I thought an audio signal coming out of an amp or preamp was a sine wave anyway.  I thought those things made the seemingly simple idea of driving LEDs to pulse with sound or music a little more difficult.  Microphone input -> preamp -> rectify it to make a nice fat on/off dc signal -> drive something.  But I see this:    with a circuit that looks like:   I see other circuits (one at Instructables I think) that essentially do the same thing- connect the line level voltage directly to some transistors.  My question: I haven't a clue what is going on here.  Why does this work- or does it really?  What is happening?  Is it that the "audio source" is really headphone/speaker level and not the line level it may be billed at and thus enough to saturate the transistor?  Does this look like a recipe for disaster?    EDIT:  Trying to focus things per Red Gritty Brick.  I know the diagram is crap.  How would you do it right?
117600
I'm using a repurposed ATX power supply for my hobby projects since it's got 3.3/±5/±12 outputs, all of which are really convenient. But one thing I didn't really think about until I slipped my probes across the pins of an opamp, since I've always dealt with commercial/proper lab power supplies in my school labs, was that an ATX power supply will gladly deliver lots of current if that 12V line (or any other) is shorted to ground. The poor LM318 didn't stand a chance. My meter and supply survived, but in the interest of not killing anything in the future, myself included, I was wondering what the best option was for short/overcurrent protection?  I was thinking of sticking some high wattage resistors at the output of the supply before connecting them to the rails of my project breadboard (I use a separate breadboard with terminal blocks for power, which the ATX supply connects to). The problem is if I'm drawing a lot of current (LEDs etc) this will sag the voltage on the line. And, for example, if I use a 1W 200ohm resistor on the 12V line, it limits my current to only 60mA - if I want more, I need some really beefy wattage resistors. I can probably work around the voltage sagging by using a voltage regulator (eg at 10V), but this all doesn't seem like the best way to go about doing things.   I'd appreciate some input from someone more experienced than I am.
1040
I have a front end module that generates an (ECG) signal that varies from +/-2.5 V. I want to shift this signal to 0 - 5V. What is the best way to do this? Would a summing amplifier like the below circuit good enough? With R1 = R2 and V1 = 2.5V, V2 = my signal, V3 = V4 = GND
66467
Capacitors and inductors are .    A transformer is made of two inductors, and transfers power through , through the magnetic  (right?)  Also, you can vary the ratio of voltages or currents by changing the ratio of turns on the core.  You could think of this as coupling a single primary loop with many secondary loops, and then stacking the secondary loops so their output voltages are summed.  Is there an electric dual of the transformer?  Something that uses capacitance and transfers power through the electric near-field over an isolation barrier?  Some way to couple a single primary capacitor with multiple secondary capacitors and then stack them to do power conversion by summing their outputs?  I know that an isolated supply can be built using two capacitors, but I'm not sure if that's exactly a dual, or if there's an equivalent to adjusting the ratio of turns:     Or maybe something related to this?      For example, there are capacitive voltage dividers, but these only reduce voltage, they can't increase it like an autotransformer.  There are charge pumps, but those require active elements like switches or diodes, which aren't present in a transformer.  More succinctly: Is there a way to transform power (1 V, 5 A on primary to 5 V, 1 A on secondary) using electric fields instead of magnetic fields, and passive components only?  If not, why not?  (Electric field screening?)
101729
Does anyone know if a finite number of parallel-series impedance has a general solution?  I am trying to model a network flow problem that can be described in electrical terms and represented as a finite discrete transmission line with arbitrary impedance.  While it is not difficult to write the equations down for a small number of terms, I'm curious if there are some general solutions or insights into the problem.  It looks like  ----Z1---+----Z3---+----Z5---+---...---+          |         |         |         |          Z2        Z4        Z6        ZN          |         |         |         | ---------+---------+---------+---...---+   All the Z's are, in general, different.  I'll need to know the "current" and/or "voltage" at every branch. In this case the bottom is grounded.  What would be cool is to be able to know the voltage and/or current in terms of i, the ith position (the top +).  Any ideas?
103796
I was running through the datasheet of  (Low-Cost Low-Power 2.4 GHz RF Transceiver) which has a dimension of 2.40mm X 2.40mm approx. It was really amazing to find such transceivers to be fabricated in such a small area.Infact a transceiver requires a lot of R,C and even L.Resistors, Capacitors and semiconductors are easy to be imagined on an IC but an Inductor!!!  I haven't work in any VLSI industry so it would be great if someone can tell how these inductor logic is implemented on IC. Although it is said that  are alternative solution, but thanks for pointing if my knowledge is correct.
3194
The basic amplification schematics shown in the  datasheet shows a 250 uF capacitor in series with the output. I don't have any 250 uF, but I do have plenty of 470uF. If I understand correctly, is this capacitor used as a high pass filter, so should I be able to use a 470 uF instead of a 250 uF?   Also, is the resistor (10 ohm) and capacitor (0.05 uF) going to ground a low pass filter?
42748
I am struggling to understand two things about this circuit.  1) when input and output terminals are open circuit, why is this assumed to be in active mode?  2)What range can the quiescent output voltage of the amplifier be in?  Now I know that active mode you need EBJ to be forward bias and CBJ to be reverse bias but how would this apply in this scenario?  I understand what quiescent voltage is but I am struggling to apply his here with the input and output terminals. I would appreciate any help.  Many thanks.
108717
I'm trying to drive a gyroscope that needs a 3 phase 400Hz 32v 1A power supply. How can I provide that supply? It's one part of my university project and I'm a beginner in this field. I'd like to find the best way  to provide a suitable supply. thanks
8639
We have this transformer:     &ndash; Schematic created using  The power transfered to R1 resistor is maximized when the frequency of the signal is very big.This means   it is not useful to use the same circuit for low frequency signals? If I want to send a low frequency signal and want as much power as possible to be transfered to R1 resistor how do I achieve it?
19342
What is the difference between the Resistance and Impedance? When we will say it is an Impedance and when we will say it as an Resistance? Can you explain it with diagram (If possible) and real time example.    And how the reactances will form in the circut where the Capacitors and inductors are not available in our circuit? How we will find the reactances in the circuit and its values in real time?   I means is this possible to calculate the reactance by using any instrument? Do the reactance was intentionally kept by the designer or generally it'll forms with in the circuit?   All answers are appreciated.