# Tag Info

89

There's no such thing as "lossless" anything in electronics, and there's not a single IC that's designed to do what you want. But here are some different supply ideas. Since you didn't specify current consumption or efficiency, let's look at three different approaches: Non-isolating Zener supply 5% efficiency or less Plug-in timers that are ...

57

It breaks up into three simple sections that are each relatively easy to explain: simulate this circuit – Schematic created using CircuitLab The first part is the diode that provides reverse voltage protection. If for some reason the polarity of the input voltage is wired opposite to what it is supposed to be, then $D_1$ will block it and the ...

24

Power output and energy per switching cycle An output of 265 volts at 5 mA is a power of 1.325 watts and this means that the energy that needs to be transfered each switching cycle is 1.325 W divided by the switching frequency. Hence, the energy released by the flyback transformer is 2.65 µJ. Accounting for losses, you should probably bump that up to around ...

18

The TIP41A is configured as a voltage follower. The emitter voltage will be equal to the base voltage minus about 0.7 V. The 470 Ω resistor provides the base current to turn on the transistor and pull the base towards the supply voltage. The zener diode will turn on if the base voltage goes above 9.1 V (its breakdown voltage). Therefore the base will be held ...

15

Flogging the FREDs Voltage fed converters with transformer isolation will exhibit ringing in the secondary. Ringing is caused by parasitic inductances and capacitances in the circuit, with the dominant elements will being the transformer leakage inductance ($L_ {\text {Lk}}$) and junction capacitance ( $C_j$)of the bridge diodes. The diode data ...

14

I know it's an old question, but you might want to see the SR086. At Vout you just need to use generic dc reg (e.g. 7805) to get your 5V. Note: This is not isolated, so it could be dangerous depending on the situation.

12

There are a few reasons. Polarity Ćuk converters must always have opposite input and output polarity. This makes them somewhat inflexible and would prevent them from being used in any application that simply wanted to reduce/buck or raise/boost the input to output voltage. The only way a Ćuk converter could do what the buck converter you linked does is ...

12

NAMUR is a signaling standard, used primarily on proximity and limit switch devices. It outputs a current signal depending on the state of the switch. The switching spec is >2.1mA (typically but not always for NC) and <1.2mA for the opposite switch state. There is a 0.9mA deadband for noise immunity. The output is usually characterized at an output of ...

11

That's normal behavior for an unregulated power supply. An unloaded transformer will give a higher voltage than nominal. Putting some load on it will drop the voltage quickly. For the Arduino I would suggest to use the 9 V setting, so that the Arduino's voltage regulator doesn't get too hot when you would power several things (like a lot of LEDs) from the 5 ...

11

Design Requirements restated from the question: - Vin = 5V nominal (I assume 4.75V minimum) - Vout = 12V nominal, +/- 0.5V ripple - Iout = 15mA peak Since I'm an applications engineer at Maxim Integrated, I did a quick check for parts we make that can meet those requirements. Regardless of whether you buy from Maxim or not, it's worth looking at the ...

10

I would like to use a DC-DC converter to adjust the voltage and the current too. I would like to adjustable the voltage and the current too in the same time. It doesn't work that way. A power supply can control one degree of freedom, such as the voltage or the current, but not two. The load determines the other degree of freedom. For example, if you ...

9

This is a classic snubbering problem. A diode can't instantaneously go from conduction to blocking; the charge in the PN junction needs to get swept out, and an RC snubber across each diode should help this. I used to design industrial soft starters and on the medium-voltage units we had a lot of design work around this particular aspect. It's been a long ...

9

Overly simple explanation alert!! In very simplistic terms, a boost converter circuit looks like this: - To the left is the power source (48 volts) and to the right is your load. In between is a switch (usually a MOSFET) that "shorts" the inductor to 0V for a short period of time then the switch goes open circuit. The inductor will accumulate energy ...

9

N is TI's designation for their Plastic DIP through hole package. Note that the SMD SOIC package designation is M. Note, these are old ICs first designed by National Semi in the 1970s (This App note is from 1976) and later cloned by everybody. TI eventually acquired NatSemi in the 2000s and absorbed their ICs into their product lines. I believe but can't ...

9

do they try to hold the output voltage constant Yes they do, these converters are mostly used for supplying a circuit with a constant supply voltage. Although it would be possible to make a converter where $V_{out} = n *Vin$ there is not much use for such a circuit. Most circuits rely on/need a constant supply voltage. Ideally you want the output voltage ...

9

The 4 diode bridge is a full-wave voltage doubler and achieves 200% of the voltage and 50% of the current of the centre-tapped 2 diode full wave version. Thus the tapped version has lower impedance. Some users might consider the tapped 2 diode version as a 2 phase each half wave combined to make a full wave. But in fact, the secondary is only a split-...

8

Old but actual question. After evaluating tens of approaches for AC/DC power converters I concluded following (for myself). Requirements: Small size as possible. Less components as possible (footprint, size, price). Less heat dissipation (efficiency in other words). Low current, very low voltage, low output power. Gave up requirement: Isolation: in my ...

8

An analog signal that is sampled is called a discrete-time signal. An analog signal that is quantized is a discrete-valued signal. A signal that is discrete in time and amplitude is called a digital signal. ￼

8

Yes, it works — at a very basic level. But no, it cannot adjust the signal timing, which must be correct to begin with. All this circuit is doing is combining the five VGA signals (R, G, B, H and V) into a crude approximation of a monochrome RS-170 signal. The resistors at the top do a rough weighting of the three color channels to approximate how the ...

8

All modems are PHYs (physical layers) in the OSI network model, but only some PHYs are complex enough to be considered modems. Why? I think it depends on four things: simple or complex modulation carrier or baseband WAN or local historical use For example, an Ethernet PHY uses simple encoding depending on the speed in use (MLT, PAM). These schemes have a ...

8

If it is confirmed the MOSFET needs a better drive then the best is to advise a suitable circuit. A simple bootstrap circuit described by Monsieur Balogh in a TI application note can do the job nicely in a cost-sensitive application. As noted in some of the comments, the UC384x was not really meant for hi-side drive - unless you make it entirely float and ...

7

If you have the exact NPN equivalent you only need to mount the circuit as it is drawn, so that the base, collector and emitter terminals of the NPN are connected where base, collector and emitter of the PNP should go, and then reverse the power supply polarity. This trick works in most cases, but it depends on the circuit we are speaking about. The exact ...

7

For a well done project? Very, and Expensive. You would need to source a proper Mini DisplayPort adaptor, then figure out how to turn a digital dvi signal to display onto two monitors while the computer only sees one. And if you want thunderbolt? Forget it. Outside of any conceivable student range or pricing. According to MSI, a huge manufacturer of ...

7

The ESR of the capacitor forms a zero at frequency fz = $\frac{1}{2\pi\cdot\text{ESR} \cdot C}$, which tends to reduce the stability excessively if the ESR is too low. The ESR also should not be too high, of course, so usually there is a recommended range. Older parts that were designed before high-capacitance ceramic parts were ubiquitous may omit ...

6

I am mildly surprised that while the Non-Isolating Zener Supply was provided, there is no mention of a non-isolating capacitive reactance circuit voltage divider. If the device functions within a narrow current requirement, this can be reasonably efficient. The chief issue with the design (well, besides not providing mains isolation) is that you cannot use ...

6

The nearest I can find is this device: - With a 0.5V input it will produce 5V but only with probably 50mA output (Green graph for TPS61202): - Hopefully it'll work for your application

6

I know the questioner has accepted an answer but I don't think it is sufficient as it stands so I'm offering what I consider to be a better take on things. The main problem is that I think the wiki article could be better too. It states that a boost converter is type of SMPSU.... ... containing at least two semiconductor switches (a diode and a transistor)...

6

There are some cables that convert directly from USB to RS-232, all of these should say so and all should be (reasonably) compliant with the RS-232 specification. However, there are also lots of cables that translate from USB to TTL asynchronous serial data, and these will be rated at either 3.3V or 5.0V. Such a cable needs a separate TTL-to-RS-232 ...

6

The short answer is it represents the resolution of the analog to digital converter (ADC). An ADC solves the problem of getting a digital device (something that only deals in 0's and 1's) to understand an arbitrary analog voltage. The 8 bits represent a binary number between 0 and 255, which are 256 unique numbers. The chip uses a conversion method called "...

6

You have not mentioned it, so I'd guess you're driving the MOSFET directly from the Arduino. That alone would explain the large dissipation, as an MCU GPIO pin is simply not powerful enough to drive a power MOSFET directly. The IRF3205 is a non-logical-level MOSFET, so even the driving voltage alone may be insufficient (logical-level MOSFETs can be driven ...

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