Posts by Olin Lathrop
Your circuit It doesn't make sense that the yellow blob is a current sink: If it were a current sink, then there would be no point to the resistor in series with it. That only wastes power, re...
At first glance, your design looks reasonable. I assume D1 and D2 are really supposed to be on opposite data lines, and them both being on the A line is a typo? One thing that sticks out to me is...
Is there a scientific way to estimate the resistance of a pogo pin? Ultimately there must be, but it generally requires knowing things you don't know. Worrying about the resistance of the barrel ...
My first knee-jerk reaction was to use opto-isolators. There are some that have been around for decades and are unlikely to go obsolete any time soon. I wasn't previously aware of these "digital ...
It has two female inputs on the backside that are labeled as "Grounding". This is incorrect. Take a closer look at the two connections and you will see that the left is labeled "Antenne" and t...
Thanks for asking. In my view, if it's something you'd first think of asking an electrician, it's probably off topic here. That includes what type of cable to use, whether it should be in a condu...
What you basically ask for can be done (I've done it), but not all your specific constraints can be reasonably met. The way to measure transmission line impedance is to drive a step onto the trans...
Yes, votes on meta should not factor into rep. Meta downvotes indicate disagreement, not that you're a terrible person, have the IQ of a garden slug, and cast dispersions on your heritage like the...
Starting with your first circuit: It seems a little klunky, but should work. I don't like the D1 and D2 diodes. The reason I placed D1 is to avoid triggering the mosfet with very low voltage li...
Your third equation defines impedance. Rearranged to solve for Z, it is: Z = V / I Note that this is exactly Ohms law when V and I are real numbers. In the general case of impedance, all th...
Follow the current. Q3 is a controlled current sink. Whatever voltage is applied to its base appears across R11 minus the B-E drop. That voltage on R11 causes a particular current to flow. That...
EMPs (electro-magnetic pulses) occur naturally often. Every lightning strike is one example. Larger EMPs have been created artificially with nuclear weapons. The Starfish Prime H-bomb test cause...
To summarize, it seems you want a circuit that will detect an input voltage high/low with a threshold somewhere between 0 and 3.3 V, must operate correctly with 0-3.3 V input, but must tolerate inp...
Voltage Rating If a device says it needs a particular voltage, then you have to assume it needs that voltage. Both lower and higher could be bad. When no tolerance or input voltage range is specif...
First Circuit Let's start by looking at the conventional current mirror circuit: The base of Q1 (Not sure which one that is? Use component designators next time!) is driven to whatever it takes...
I always had trouble understanding the terms "digital" and "analog" A digital signal is intended to indicate one of a finite set of discrete states. The number of discrete states is usually two fo...
You haven't provided any context, so there is little to say about this particular design. For all we know from what you told us, this could be homework from a student that just made a mistake. How...
Roughly around 27 MHz is the old "CB" (Citizen's Band, 11 meter) frequency block. The advantage of this band is that it is free to use with limited power. This is the band "walkie talkies" used t...
1 - Signal 2 - GND 3 - PWR 4 - Signal This seems to be common advice, especially on the 'net someplace, but that doesn't make it good. Stop and actually think about what problem you are trying to s...
First, let's be clear about something. All currents partially take all paths relative to the inverse of the path impedances. It's not an all or nothing function. This "Takes the path of least re...
You generally want complementary NPN/PNP pairs when they are used as opposites of each other in the same circuit. One transistor is usually used with opposite polarity as a mirror image of the oth...
Pi filters are often used to block high frequencies between a device and the power line it draws power from. In such applications, the considerations specifying the inductor include: How much powe...
First let's define what a "Pi filter" is: The name comes from the inductor and two caps forming the shape of the Greek letter Π. These filters are used for EMC compliance because they attenuate hi...
The short phrase is trying to capture the two broad classes of topics here: Electronic things, like opamps, transistors, microcontrollers, 20 W power supplies, and the like. Utility-scale power sys...
My control system gets a signal representing the plant output, but that signal has a lot of noise on it. The control system goes nuts trying to react to the noise. I need to filter out the noise ...
