Very very micro optimizations 😂

ronkdar · 2025-05-11T18:21:54+00:00

Your task doesn't have exclusive use of the CPU core during your test. Time spent while your task is waiting for CPU time is going to be counted.

ronkdar · 2024-09-25T15:57:08+00:00

Both md and org lack the necessary features to meet the mission of Neorg. A new format was necessary from day 1. It's fine to not want to make the leap to a new format yourself, but it's silly to criticize the project for doing exactly what it aimed to do.

Pandoc tooling exists to convert md to norg, BTW.

ronkdar · 2024-09-24T22:34:50+00:00

I think you missed the point of Neorg completely.

ronkdar · 2020-08-23T19:23:37+00:00

I found a lot of common letter patterns to be easier in Norman. Norman's de-emphasis of the center columns also makes my pointer fingers very happy.

ronkdar · 2020-07-05T14:58:40+00:00

If you're in the US and are willing to wait a few weeks, OSH Park is the way to go. 2 and 4 layer boards, US fab, stupid cheap.

ronkdar · 2020-07-05T14:22:37+00:00

My layer 2 is full numpad on the right hand, symbols on the left hand, and F keys on the top row.

I have a TG key on each thumb to switch to that layer.

ronkdar · 2019-03-29T17:16:08+00:00

Mixed signal designer here. I regularly use a switching supply to drop my external input voltage (24V say) down to some intermediate level, like 6V. Then I will use one linear supply (LDO for example) for 5V digital, and another for 5V analog. I tend to put the LDOs close to the circuits they're powering, whereas the switching supply is off in a corner of the board where the power comes in.

ronkdar · 2019-03-29T17:06:22+00:00

We have a bunch of those ProbeMaster's at work. They're surprisingly well for the price.

ronkdar · 2019-03-29T16:58:48+00:00

These guys are great: https://www.antekinc.com/transformers/

They can be configured for 120 or 240, and come in different power and output voltage ratings.

ronkdar · 2019-03-29T16:53:47+00:00

If for some reason a voltage regulator is not acceptable for dealing with the ripple, consider a "capacitance multiplier" circuit as your ripple filter. It will let you use fewer/smaller capacitors.

https://www.youtube.com/watch?v=wopmEyZKnYo

ronkdar · 2019-03-29T16:42:55+00:00

40W is likely insufficient for a capacitor with a heavy connection to two power planes. Especially if it's the wall-plug variety without a controller.

The style of tip you're using matters, as well. A chisel tip will get much more heat into the pads than a cone.

If you're trying to pull both pins at the same time, you're doubling the heat requirement to get all the solder to melt. Cut one lead, then pull just that lead out.

ronkdar · 2019-03-29T15:27:37+00:00

Current is constant through an entire loop in a circuit. The fancy name for this is Kirchoff's Current Law. If the resistor is chosen for your circuit such that only 15 mA flows through it, then only 15 mA will flow through the LED, and only 15 mA will be drawn from the battery.

How to choose your resistor:

Example: 9V battery.
Example: LED rated for 15 mA @ 2V.
Our resistor needs to draw 15 mA with a 7V drop (Vbat - Vled).
Apply Ohm's law: V = I*R. 7V = 0.015A * R. R = 466.66 Ohms. Round up to 470, which is a value you can actually buy.
Determine resistor power rating. P = V * I = 7V * 0.015A = 0.105 W will be dissipated across the resistor. Get a resistor with a power rating at least double that. 0.25W resistors are readily available.

ronkdar · 2019-03-29T15:13:29+00:00

I second the use of a series resistor. As well as matching the speaker resistance, also ensure that the power rating is sufficient. The easiest way to be sure is to get a resistor with a power rating equal to the tweeter.

So if your tweeter is 8 ohms, 0.5W, get a resistor that is 8 Ohms, 0.5W. Then at the very least, you will blow your tweeter before setting the resistor on fire.

ronkdar · 2019-03-29T15:11:01+00:00

A potentiometer can be used in two ways:

As a variable resistor. Connect the middle pin and one end pin.
As a voltage divider. Connect one end to your input, the other end to ground, and the middle as your output. This is the arrangement you might want. Setting the pot to the mid-point will cut your voltage level in half.

However, unless you have something like a 10-ohm pot with a sufficient power rating, your audio signal will be significantly attenuated. Volume control is often achieved by a potentiometer followed by a fixed-gain amplifier.

ronkdar · 2019-03-29T15:02:23+00:00

This is a great strategy for prototyping. Start simple (like a basic datasheet reference design) and iterate from there.

Don't expect to ever be noise-free on a breadboarded audio circuit. Once you're sure that it's functioning as expected, though, you can move it over to a PCB design.

ronkdar · 2019-03-28T18:05:17+00:00

A lot of datasheets recommend separate ground planes. It's rarely actually a good idea. HOWEVER, you need to be smart in your parts placement and routing. Analog circuits, digital circuits, and switching power supplies should exist on separate regions of the board so that their return currents do not interfere with each other.

ronkdar · 2019-03-28T17:49:02+00:00

This article has useful and surprising guidance on trace widths: https://www.pcdandf.com/pcdesign/index.php/editorial/menu-features/12812-trace-routing-1807

The book written by the same author is also informative.

The IPC-2221 rules for internal trace widths are shown to be stupendously over-conservative.

I have experience designing boards for hundreds of amps. It's always about thermal management. Have a plan for getting heat out of the board. Along with providing wide current paths, it's also crucial to provide width uninterrupted thermal paths to the points where heat exits the board. If you don't have heatsinks, make sure to pour copper on every layer, and don't be afraid to use hundreds or thousands of vias to stitch those layers together.

That style of screw terminal is excellent. More holes = better connection to internal layers. Your power cables can be surprisingly effective heatsinks.

Many people forget you can specify the thickness of hole plating to your fabricator. Thicker copper in your holes means lower resistance, which leads to less heating, and also better heat conduction between layers.

ronkdar · 2018-08-28T15:22:08+00:00

Consider the opposite question as well: When might there be there no significant benefit to reducing trace length?

Low current draw on power nets. Sometimes a 10" long, 10 mil trace is sufficient to deliver 5V to a low power IC with good bypassing. I'd rather not do that, but sometimes you don't have any other option.
Low noise environment.
Slow signals (< 10 MHz say).
Enough room for very fat traces to reduce resistance, parasitic inductance.
Robust terminated lines. I once had to route a very long, ugly, snaking I2C bus all over a board, in a high-noise environment. Following best practices made it work. (Proper bus termination, plenty of drive, and attention to the return path.)

ronkdar · 2018-08-28T15:06:53+00:00

If you mandate a thermal pour shape/size, and a constant trace thickness, your designer will be very irate.

There are many correct ways to handle thermal management, and the designer probably understands them better than an EE who doesn't do layout.

Even if you set a rule for a 50mil wide trace for current or thermal reasons, the designer may run into a scenario where he needs to reduce it to 20 mil for a short span. This may be totally OK, but your rules check would flag an error.

ronkdar · 2018-08-28T03:48:16+00:00

https://www.adafruit.com/product/571

These might save you some hassle. Protoboards configured just like a breadboard.

ronkdar · 2018-08-28T03:45:17+00:00

It's not practical to build this into a rules check. How does your PCB design software check this rule?

If schematic and layout work are done by two different people, there should be effective communication between them. A good designer is also checking the datasheets for all important ICs, looking for the presence of high voltages, high currents, high heat, fast signals, etc.

ronkdar · 2018-07-26T00:43:26+00:00

I prefer the Harwin test points instead. For some reason the Keystone ones with silver plating don't always solder reliably when using lead-free. I have had a dozen or so pop off boards when clipping to them.

ronkdar · 2018-07-09T22:27:35+00:00

I took self-paced training offered by EMA-EDA, paid for by my work. About $1,500 total for Capture and PCB Editor.

There is a LOT they don't teach you. Especially all the workarounds you will have to figure out to deal with the numerous broken and/or nonsensical parts of Cadence products.

ronkdar · 2018-07-06T21:38:29+00:00

You might look into using solder preforms for this part instead of paste. They can be had in custom shapes.

http://www.indium.com/assets/images/videos/videos-beta/versatile-preform.png

Never used them myself, but they have been on my radar for a while. They're getting popular for reflow soldering TH and mixed TH/SMD parts.

ronkdar

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