New answers tagged

2 votes
Accepted

Measuring current of GUVV-C20SD diode with transimpedance amplifier

I have checked out the following image and I don’t understand the function of the 51k resistor. Normally, designers put a resistor in series with the non-inverting input to balance the impedance seen ...
user avatar
  • 390k
9 votes

Can ULN2003 be a poor-man’s matched diode array?

I think the answer is a qualified yes, at least at DC. I haven’t checked anything at AC just yet. Results so far: I’ve picked 5 ULN2003 from the junk bin - all different lots, and from at least 2 ...
user avatar
4 votes

Can ULN2003 be a poor-man’s matched diode array?

The CA3046 transistor array can be used to provide a minimum of 4 B-E diodes. This is a monolithic die which guarantees the diode matching to 5mV, and the thermal matching should be excellent.
user avatar
  • 1,015
12 votes

Can ULN2003 be a poor-man’s matched diode array?

I've measured thermal tracking on SOT23-6 dual matched transistors like DMMT3904, by sending a current pulse in one transistor and measuring the Vbe of both. Thermal coupling is very poor. They're two ...
user avatar
  • 62k
5 votes

Can ULN2003 be a poor-man’s matched diode array?

It should work. You might have to connect the GND pin to a negative bias point to keep sneak paths from conducting. They're diodes so they don't respond in as ideal a fashion as diode-connected ...
user avatar
7 votes

Can ULN2003 be a poor-man’s matched diode array?

While the datasheets don't specify any of these diode characteristics, at low currents (say < 10 mA), where the resistance of the metal interconnect won't come into play, they will likely match ...
user avatar
  • 15.5k
0 votes

How do I solve the current of this circuit with a diode?

Nodal equations are your FRIEND. Let V_a be the voltage at the diode anode. You can get away with treating the diode as a pure voltage source and ignore its resistance (which will be MUCH less than ...
user avatar
0 votes

What would be the loop equation for circuit including resistor, diode, light emitting diode?

This is one of those you can just eyeball, rather than writing and solving equations. Assuming a Bog-standard red LED, Vf = 1.7V. That leaves 1.3V across the 100 ohm resistor, for 13 mA through the ...
user avatar
0 votes

What would be the loop equation for circuit including resistor, diode, light emitting diode?

There is a approximately answer: there is no current between diode and LED. LED voltage is approximately 1.5 V. V(r100)=3-1.5=1.5 (V). I=1.5/100=15 (mA) Normally 15 mA is more than LEDs saturation ...
user avatar
4 votes

What would be the loop equation for circuit including resistor, diode, light emitting diode?

The simplest way is to just use KVL and ideal diode approximation then guess between one of the four combinations of diode operating conditions: [conducting, blocking], [blocking, conducting], [...
user avatar
  • 48.3k
1 vote

Do I need a diode in my circuit when using a USB-powered DC power supply to power a laptop camera?

If you are using an SMPS, such as a desk top power supply, they have a 3.3 volt rail which can be used to power a camera, for example. With a switched-mode power supply, such as a desk top supply, the ...
user avatar
0 votes

Need help identifying SOD-123 packaged Zener diode with WG G0 marking

BZT52C10 or 11 seems correct, from several manufacturers: https://smd.yooneed.one/code5747.html https://www.s-manuals.com/smd/wg
user avatar
  • 5,124
1 vote
Accepted

TVS with and without VDD connection

It depends on the topology of the sockets you want to protect. For example, for USB where you have D+/D- and VBUS to protect, it is a good idea to have a VDD input on the protection device to cover ...
user avatar
  • 101
3 votes
Accepted

What is a field effect rectifier diode (FERD) and what is it used for?

Summary Apparently, the FERD is a technology all its own, a higher-priced higher-quality (lower forward voltage, lower leakage), or as one later-quoted source says, "achieves the best in class VF/...
user avatar
0 votes

Can I use MOSFETs as diodes in a battery backup circuit?

That type of circuit will not work as drawn because reverse voltage is not the same as reverse current protection. A true diode protects against both and but a simple PMOS circuit is not. A simple ...
user avatar
  • 48.3k
2 votes

What does it mean 'leaded' near junction-to-case resistance?

Rthj-c is the thermal resistance from the junction to the component body/case and it remains unchanged irrespective of the external thermal arrangement that the designer would make. (Image source: ...
user avatar
1 vote

I don't know what this dimension means for a diode package drawing

Usually "Φ" denotes diameter. That's the uppercase version of "φ". I think it's a typo, where they got the case of a Greek letter wrong.
user avatar
  • 9,286
1 vote

Protecting only part of a circuit from reverse polarity?

That should be OK, but it looks like the analog circuitry in the schematic shown has a relay that connects 12 VDC to an external fan. The fan connector has one pin connected to ground. The relay is ...
user avatar
  • 1,131
2 votes

I don't know what this dimension means for a diode package drawing

Diameter is a slashed 0: Ø, not the Greek letter phi φ.
user avatar
  • 10.3k
4 votes

I don't know what this dimension means for a diode package drawing

The package (not including leads) is a cylinder 3.0mm in length and 2.6mm in diameter (⌀). Note Mattman's comment on the character identity. The careful engineer or typesetter will not confuse any of ...
user avatar
2 votes

How can I drop the voltage of a 5V DC power supply from 5.5V to 5.1V?

I think noise suppression is your friend here. As demonstrated in the comments, using batteries (a noiseless supply) significantly improved the voltage range that the panels could handle. They, given ...
user avatar
3 votes

What are the purpose of the extra diodes in this peak detector circuit (LM1815)?

You’re looking at a block diagram: it is a somewhat abstract depiction of what is going on. The diodes on the block diagram are not literal components. They are blocks, just as the rest of the ...
user avatar
1 vote

Looking for advice to prevent reverse current flow

typically, I would use Schottky diodes for such application. The main reason for this type of diode is the low forward-voltage drop (meaning you want to conserve voltage for the rest of the circuit ...
user avatar
  • 71
9 votes
Accepted

What are the purpose of the extra diodes in this peak detector circuit (LM1815)?

The actual (but probably still a bit simplified) circuit has no diodes, but a Darlington-ish pair Q23 and Q24 and the other lone "diode" is Q20, Q21 and dual collector transistor Q22. The ...
user avatar
0 votes
Accepted

KVL Doubt in circuit

I think you are confused about what to do with Vf because its value is negative. I suggest that you explicitly draw an ideal voltage source connected to node F and label it with the appropriate value. ...
user avatar
5 votes

How can I drop the voltage of a 5V DC power supply from 5.5V to 5.1V?

In comments, after suggesting this: Why don't you try supplying the panels using battery power, say 9 volts of AA's, followed by an LM317T voltage regulator having a potentiometer voltage adjustment. ...
user avatar
6 votes

How can I drop the voltage of a 5V DC power supply from 5.5V to 5.1V?

A big high-power Schottky diode as suggested by @user4574 is a simple approach that should be considered. In a similar approach, a saturated power-PNP transistor might work too: simulate this circuit ...
user avatar
  • 18.9k
16 votes
Accepted

How can I drop the voltage of a 5V DC power supply from 5.5V to 5.1V?

There are a few options here. This is probably the cheapest and simplest method. Put a Schottky diode in series with the output of one of your power supply bricks. You say the output was between 5....
user avatar
  • 10.2k
5 votes

How can I drop the voltage of a 5V DC power supply from 5.5V to 5.1V?

some kind of Zener shunt regulator Zener's idea is not really useful with heavy loads. I should use preferably the idea of using automatic step-up-down boards. Ok, not so simple a circuit as Zener. ...
user avatar
  • 6,124
1 vote

How can I drop the voltage of a 5V DC power supply from 5.5V to 5.1V?

I would say that this answer by "The Photon" could solve your problem. In my opinion the best option for you would be a buck converter due to the high current demand. Something to be aware ...
user avatar

Top 50 recent answers are included