# Tag Info

1

Much trial and error and frying of diodes later (best to draw a veil), this is what I know: Yes, PW is a photoresistor (thanks to venny). No, the arcs do not represent variable resistors, they just show that the switches are rotary. Neither the switches nor any of the solid-state components were faulty. It is true that the photoresistor was not the problem ...

0

It is possible that the original transformer has a double primary (0-110,0-110) currently wired in parallel, and that these only need to be changed to be wired in series instead. However, you also need to check out whether it is the only thing running on the mains supply, as others have mentioned.

0

Why don't you just buy a 230V to 110V transformer like one of these: - Then you don't need to dismantle the MIG welder and try and fit a new transformer. It was probably converted to 110V in the first place so it could be used outdoors on a regulation 110V "safe" isolated supply. If you convert back to 230V then you limit the places it can be used in the ...

1

If the intended output of the transformer is 24VAC, you can put any transformer in that gives the same 24VAC output at your desired input voltage. You can even make it a 12VAC in to 24VAC out, or 2kV in and 24V out, as long as the transformer is made for all voltages, properly insulated and has the right power (wattage). Don't go putting in a 5VA ...

1

The zener diode 'bleeds' a too-high voltage at the drains of the mosfets. The diodes allow the two mosfets to share one (power?) zener diode.

5

The voltage on the windings of the transformer obviously get pulled down to 0V by their respective MOSFETs but when a MOSFET is open circuit, the voltage on its winding rapidly rises to twice Vcc (24V) because the other MOSFET is rapidly pulling down the other winding to 0V. Think of it like a see-saw with the pivot-point at 12V. But, there is a small ...

0

*Change resistor for RESET pin to 10K. *Add a 100nF cap between AREF and GND pin. *Add 100nF capacitor between each VCC pin of your ICs and GND. *Connect GND pin of USB to GND. *Connect VOS of TPS62172 to VCC!!!! *I can't find GPSTX label! where it should be connected! *Connect LED1 to GND. Your L2 has no value, it should be 33nH. I think revise ...

1

For each element, compare the sign of the voltage to the sign of the current. Or, multiply the current by the voltage and look at the sign of the resulting power value. If the current is flowing from the more positive side to the more negative side, then the element must be removing energy from the circuit (dissipating/transducing it, e.g. a resistor, ...

2

A switched capacitor can be thought of as a device that converts a frequency into a conductance value (i.e., the inverse of resistance). Therefore, you might consider a circuit something like this: simulate this circuit – Schematic created using CircuitLab It can be shown through a simplified analysis that the voltage on $C_{filt}$ is: V = ...

4

Q1 is the oscillator transistor. It's what provides the gain to sustain the oscillation. The entire oscillator is formed with Q1, L1, C4, C5, R3. C5 is what provides the feedback that keeps the oscillator running. R1 & R2 bias the transistor in the linear region. C2 makes the base of the transistor appear to be grounded at the oscillator frequency. ...

5

This is a variation on a Colpitt's oscillator. L1 and C4 make up the main LC resonant circuit. C5 is used to provide feedback to the emitter of the transistor which amplifies the signal and makes up for losses and the power radiated from the antenna. The transistor is in a configuration known as "common base" or "grounded base" as the signal to be ...

5

L1 and C4 are the parallel-resonant tank circuit for the RF oscillator, and Q1 is wired as a common-base amplifier that provides the gain required for oscillation, with the feedback (and output coupling) provided through C5. In the common-base configuration, the input is applied to the emitter and the output is taken from the collector. The base is held at ...

3

That's an N-channel MOSFET, which is a bit like an NPN bipolar transistor but doesn't require any gate current. The three terminals are Gate (at the left), Drain (at the top) and Source (at the bottom). The Gate is equivalent to the base of a bipolar transistor, drain to the collector and the source to the emitter. MOSFETs have a diode in parallel with ...

2

This is an NMOS, have a look here. The part that might have mislead you is probably the diode from source to drain: this is called body diode and is a sort of side effect component. When you integrate a power mos on silicon you get that extra diode, that can somewhat sometimes be helpful.

0

When working with EE, there are two things to remember: superposition and symmetry. In this case, the symmetry is pretty clear, so DDR_VREF = 1V5_DDR/2.

2

The capacitors don't conduct when the supply is pure DC so ignore them. Next use ohms law to calculate current through R11 and R12. Hint Rtotal = R11+R12. Next calculate the voltage across R12 given that current you just calculated. Or, you can just simply look at it and notice that R11 and R12 are the same value hence the voltage at their midpoint is half ...

3

Q2 and the circuit around it form a Colpitts oscillator. This makes use of the fact that a transistor in the common base configuration can have voltage gain from emitter to collector. Consider this simple circuit: When IN is biased so that OUT is near the middle of its range, then small voltage changes in IN cause large voltage changes in OUT. The gain ...

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