Posts by Andy aka
Equivalent Circuit, 1:1 transformer Start by simplifying the circuit and change the transformer to a single inductor. This simplification ignores the benefits of isolation but, flyback converter t...
Why are some PCB design software programs considered to be 'hobbyist' programs? Elitism and, folk with money to burn. I've used Altium, PADs, OrCad, Eagle and my current personal favourite is...
The lifetime rating is (usually) quoted as "so many" hours at a certain temperature and that is the crucial thing to be aware of. For instance, consider a capacitor like this one: - Some in the ...
If the data sheet doesn't indicate that the two devices are matched then sorry, they probably are not and, you should use a matched device like the PMP5201Y that you linked. That data sheet mention...
Why am I getting these downvotes? It started last week (or the week before) and now it seems like it's getting contagious: - Seems like this site has some of the same outrageous inclinations as ...
Which graph on the picture above better represents real-world use-case? They both represent real-world use cases. The impedance graph informs you how much ESL (effective series inductance) the...
I need to design a simple flyback converter like this: - I want to control duty cycle from another circuit such as an MCU but, I'm unsure how to proceed. My requirements are: - Input voltage 125 ...
To add to Olin's excellent answer, if you were probing on a digital IO line in order to view a fast changing signal, without the local ground clip (or spring) grounded close to where you make the m...
Try this out for size: - Hope it's clear. Maybe a little simulation of 10 km 600 Ω line might help paint a better picture: - The voltage (V1) that feeds the t-line via the 100 Ω lamp is a 1 v...
I have recently finished designing a buck-boost converter for a job that uses a split (+/-) input power supply. Load power is taken equally from both positive and negative input supplies and, the ...
A taper pad is a resistive attenuator that maintains impedances on both ports and provides a specific amount of gain-loss ($A_{12}$): - I have derived formulas for each resistor (that I know to ...
Is there any way to reset a core quickly without having ground / reference terminal pulled towards negative voltage Unfortunately not but, if instead of trying to send the complete pulse throu...
Embedding pictures is a pain in the ass. First you have to find the picture and save it locally then you have to drop it onto a special box before it can be processed. On SE, you just drag it to wh...
If you search through the electrolytic capacitor offerings from distributors like Farnell, RS, Digikey or Mouser, you find that the maximum life-time rating is commonly quoted as 5,000 or 10,000 ho...
Is it because for AC signals the emitter looks like a short to ground and that essentially increases the voltage drop across the collector resistor? Yes. The gain of a common emitter amplifier is...
When should a transformer core be potted? Should it be potted at all? For this type of job, you would pot the transformer when you can't obtain the necessary creepage and clearance between the...
An important formula in physics is one that relates the speed of an EM wave (c for instance) with the magnetic permeability and electric permittivity of the medium. In short: - $$c = \dfrac{1}{\sq...
What are the advantages of such DC offset removal loop, compared to an RC high-pass filter? The primary advantage is that it keeps the front-end amplifier output centred in its DC operating re...
It's still happening: - Can someone actually do anything about this? This has happened on stack exchange before but this is ridiculously more far fetched than what has ever happened there. Do y...
How is it possible to generate 500V on a trafo secondary given the 1:1 ratio? In a DCM flyback transformer circuit, the secondary winding is being used as a pure inductor. So, once the primary...
To understand why complementary pairs are used, it's probably a good idea to think about the limitations of the NPN emitter-follower circuit: - It's a good circuit for delivering modest powers to ...
Please let me know if there is anything wrong with this logic. So far so good. The voltage clamp (3 zener diodes for European IS category iA and two for category iB) is the limiter on voltage ...
Inductance is defined by the shape of the coil, the area of the coil, the number of turns in the coil, the distance between turns, the ferromagnetic permeability of material within (and surrounding...
If you are AC coupling to a load then you need an emitter resistor to set the DC operating point and quiescent current of the amplifier. An external AC coupled load cannot do this and, it needs to ...
Since we are trying to keep the impedance matched to 50 ohms, what is the best strategy to approach this circuit? A low pass $\pi$ network seems a good route to go. Basically your $\pi$ networ...
