9 votes
Accepted

DC/DC Converter not outputting the correct voltage

Simple enough, the positive regulator is a boost converter and output cannot ever be below input voltage -once granted voltage drop on D1-
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  • 2,977
5 votes

DC/DC Converter not outputting the correct voltage

It's simply the wrong part… the LT3463A is a boost converter so if you feed it 3.5V you can't get a regulated lower voltage on the output. The topology is easily recognizable since the inductor is on ...
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5 votes
Accepted

Why is an inductor rather than a capacitor used to smooth switch mode regulators

In a switching regulator (buck, boost, buck-boost etc.) the inductor isn’t there to smooth the output. It’s there to store and release energy in a controlled way. The input switch will ‘charge’ the ...
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  • 40.6k
4 votes
Accepted

Is there a good way to insulate the backplate of a 7915 voltage regulator?

Here's how. The insulator between the device and the heat sink is a mica shim and that between the device and the screw is an insulating bushing. Image credit: Infineon.com
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  • 10.5k
4 votes

Voltage divider, linear regulator, other options to power proportional HV DC-DC converter?

As said by Andy aka, using a version with a control pin is the easiest way to accomplish your goal. However if you already have the EMCO converter and can't buy a new one (they are fairly expensive) ...
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  • 105
4 votes
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Series voltage regulator with Zener diode and BJT - equations to explain the working principles

Opening Summary The circuit is the following (you really should learn to redraw schematics for better reading): simulate this circuit – Schematic created using CircuitLab If you are willing to ...
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  • 70.2k
3 votes
Accepted

How does a switching regulator behave if its input is equal to its output?

It depends on the specific regulator. Some buck regulators have 100% duty cycle mode. In that case, the top FET turns on, and it's just like having a resistor between Vin and Vout with a value equal ...
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  • 19.7k
3 votes
Accepted

Capacitor selection with current rating for switching regulator

The info is a bit hard to find. For Murata, you can use their website (click on ceramic capacitors). Then, picking a capacitor, you can plot "Temp rise" (orange button) which will tell you ...
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  • 59.6k
3 votes

Need help identifying SMD IC

Function and pinout matches TPS560430Y, but there may be others with this pinout. The inductor 2.2 µH is a bit small for this circuit, but OK if used with <= 12 V input.
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  • 1,954
3 votes

What happens if input current of 2A is given to a L7805 rated of 1.5A?

The provided input does not matter. What matters is how much current the load consumes at 5V. The regulator can accept 12V input, and it can provide 5V at up to 1.5A. But it can't do all that ...
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  • 89.6k
3 votes
Accepted

Voltage divider, linear regulator, other options to power proportional HV DC-DC converter?

You should consider using this converter inside of a closed-loop controller. The output voltage could be precision divided down to produce (say) 1 volt out per kV in and you use an op-amp controller ...
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  • 384k
2 votes

14-Volt 6-Amp Power Supply Stability

OK, it would be better with a switcher, everyone said it. With 20V input, 10V output, 6A, the MOSFET will dissipate 60W. If there is a 6A current limit and the output is shorted, it will dissipate ...
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  • 59.6k
2 votes

How to power two ESP-01S chips from 220 V AC

The 2 most important rules of small/hobby electronics: Don't mess with AC mains power. It will kill you. * Don't reinvent the wheel. It will frustrate you and waste your time. src ** Now you only ...
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2 votes

What happens if input current of 2A is given to a L7805 rated of 1.5A?

Not knowing which brand or version of the 7805 you have, there's no way to know the specifics of how it will act. Many 7805 have internal current limiters. And thermal shutdown. One brand's datasheet ...
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  • 71k
2 votes

How to power two ESP-01S chips from 220 V AC

Be aware to know the complete specifications of the supply of ESP-01. from this link. And for the need of only supplying ESP-01S, I choose some SMPS converters (google it "AC 220V 230V to DC 3....
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  • 4,942
1 vote

Average voltage in PWM?

If you have a simple first order RC filter which removes PWM switching frequency but leaves the DC voltage, it has the correct output voltage, but due to the resistor, the output impedance at DC is ...
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  • 89.6k
1 vote

Is there a good way to insulate the backplate of a 7915 voltage regulator?

Mounting TO-220 and similar packages to a heat sink while maintaining electrical isolation is common. One example is that it allows one large heatsink to host a number of devices, each with a ...
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  • 634
1 vote

How to power two ESP-01S chips from 220 V AC

You can use a "wall wart" USB power supply with an LDO or buck regulator, or a power supply module, like this MeanWell RS-15-3.3 : It is preferable to source it through an authorized ...
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1 vote

How should I use this voltage regulator for best efficiency?

Assuming linear regulator. What features of the voltage regulator should I pay attention to for lower power consumption? Quiescent current, obviously, including feedback resistors. That pretty much ...
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  • 59.6k
1 vote

Using Jfet as constant current source to drive a BJT

I suspect that the first circuit is intended to provide a constant current limit for low load resistances. Once the voltage on the load drops below Vref, the op amp is effectively disconnected. Then ...
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1 vote
Accepted

Using Jfet as constant current source to drive a BJT

When using a JFET as a 1 mA constant current source, the maximum current that can be drawn into the TIP41 base is 1 mA and, given that the hFE of the transistor is only going to be around 50, the ...
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  • 384k
1 vote

Using Jfet as constant current source to drive a BJT

I agree with @TimWilliams that these circuits are a bit strange. But in general low noise current sources can be made with JFETs, see here. However, in these circuits, this advantage would not ...
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  • 10.9k
1 vote

Transistor voltage regulator circuit - question about voltage output control

The circuit is best understood by redrawing it to make it easier to understand. Q2 is is a simple Emitter Follower buffering the voltage on the Zener. You don't mention the Zener voltages so below I'...
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1 vote

How does a switching regulator behave if its input is equal to its output?

Depends on type. LM2596 for example, I believe can run up to 100% duty cycle, but has a Sziklai type output stage, so drops about a diode drop minimum, or about 5.8V minimum input (unless the control ...
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  • 2,813
1 vote

Can a voltage stabilizer with an offline UPS give the same performance as an online-UPS?

It works fine during a complete loss of grid power, but when the grid power flickers the cluster shuts down. The instant you lose grid power, treat it as a complete loss and drop a relay that ...
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  • 384k
1 vote

What happens if input current of 2A is given to a L7805 rated of 1.5A?

Regulating 12V to 5V with a linear regulator is a very inefficient method to do the job. With 7 volts dropped across the regulator more power goes into producing heat than actually is delivered to the ...
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1 vote

Designing A Circuit To Light An LED When Voltage Drops Below Threshold

Why are these two equations different? As far as I can tell the Sparkfun material is simply wrong. But it's hard to understand. For example, they say what will happen when \$V_{in}\$ is greater or ...
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  • 121k
1 vote
Accepted

Can I power my microcontroller system directly from a 3V lithium coincell (transient consideration)?

The nominal voltage is perfectly in spec, as pointed out by Autistic. On the other hand, ESD and hotplugging events are two different things. An ESD event can expose the circuit to thousands of volts, ...
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  • 2,424
1 vote

Can I power my microcontroller system directly from a 3V lithium coincell (transient consideration)?

It will be fine ,Volts are not too high when the coincell is fresh.Normally there are lots of bypass caps that would suck up any little spikes.
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  • 12.4k
1 vote

Connecting two voltage regulators in series to get higher voltage

If the panels match coarsely on current rating but not voltage, wire them in series. They will work at the spec of the smaller panel, which is no big deal if the difference is small. If the panels ...
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