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22

I actually prefer vias as testpoints for just the reasons you mentioned. I think it makes using a multimeter or a scope probe much easier. Which, after all, is the main use of testpoints. Where possible/practical, I like to size my vias large enough or use small plated through holes so that 30 gauge wire can easily be soldered in. Then I can clip a scope ...


21

To dissipate \$ 1\mathrm{kW} \$ at \$ 14\mathrm{V} \$ you need a resistor with a resistance of \$ R = \frac{\mathrm{V}^2}{\mathrm{W}} = \frac{\left(14\mathrm{V}\right)^2}{1000\mathrm{W}} = 0.196\mathrm{\Omega} \$. You can buy a \$ 0.25\mathrm{\Omega} \$ \$1 \mathrm{kW} \$ resistor on Digikey for $54.95 (Part no. FSE100022ER250KE). Using two or 3 of them in ...


19

I can only answer this question from my point of view, so I am doing so to start the conversation, not because I expect this to be an exemplary response! EDIT: there is a VERY good ESE answer here that I think would be of interest to anyone reading this. Let me start by saying that I am based in the UK, and work for a small, young company (I hate the word ...


17

I would say pogo pins attached to a small peg that can "bite" the pcb, similar to the following but using smaller pegs with one pin in the tip of each one.


15

It sounds like these test points were thru hole pads, not necessarily vias. Yes, you can use a thru hole pad as a test point, especially if it is not intended for automated testing. For a technician, a thru hole pad can be convenient. A pad doesn't really add cost except for using space, it is easy to hold a scope probe on it, and you can solder a wire to ...


14

The best trick is not a trick at all. It's using a thin solder and flux. Once you've identified the pins you need to use, that is. If heat is a concern, use a low wattage soldering iron. After all, these are fairly small (area wise) isolated pins. These things are made to be soldered. Surface mounted parts go through 270°C degree solder profiles! Aside from ...


14

You could do the entire discharge at the lower rate but then it would take a lot more time. When discharging at a high rate the voltage may collapse prematurely so the battery seems discharged before it really is. By combining the two discharge rates you can discharge the battery in a reasonable time but be confident that it is fully discharged. The lead-...


12

First google result for condom electronic testing: Although DUREX® condoms are now ready for packaging, they will not reach that stage until they have undergone a series of stringent Quality Control tests. This adherence to high quality standards has helped make DUREX® the leading condom brand in the world today. With a product such as a condom, where ...


12

Those LEDs have a typical forward voltage of 3V. Your multimeter's Diode/Continuity test feature reads anything above 2.8V as an open circuit. from this link The Diode Test function on multimeters isn't really intended to test LEDs. Normal diodes have a forward voltage under 1V. 'Old' Red/Yellow/Green LEDs would typically have forward voltages in the 1....


12

Test points are very useful during development. A test point can be a flat SMT pad, or a throughole pad. Sometimes, a test point has a loop for clipping a probe onto (throughole examples, SMT examples). Sometimes, these loops are used only during R&D testing. In mass production the test points are contacted by automated test equipment, and the loops ...


11

Continuity testing of an in-circuit component is not a reliable procedure, independent of signal injection and its associated risks. The component leads may be interconnected via other circuit elements, thus giving a false continuity result, where the component itself is actually not a conductive route. Regarding the risks of introducing a voltage through ...


11

If the square-wave looks fine after probe compensation and the scope passes self-check/self-calibration, then there really is nothing you can do at your level. To properly check it, you'd need a good lab and you don't have that. Presumably, manufacturer would have performed quality control on the unit and did factory calibration with equipment much better ...


11

The first thing I verify on a new board, whether it is using an internal oscillator or an external crystal, is that I have the clock frequency set up correctly. This is important because many of the peripherals, such as UART, SPI, I2C and timers depend on it. The way I verify it is to write a program with a short loop, either in assembly language where I ...


11

The problem is two-fold: you need a device that can provide the appropriate load, and you need to manage the heat. For my money, I would do the following (but see important warning about short circuiting batteries below!!): Take a length of thin wire (for example, the "magnet winding" wire you can buy at Radio Shack for about 9 dollars - https://www....


10

If I was to fully test each MCU for its correct functionality, I would build a test board for each, with an adapter or socket to aid the easy change of the IC. Connect each IO pin to a visual output such as an LED, and program it with a simple firmware that will test each pin in turn. A further step would be to test the communication and other features ...


9

It's hard to say what "typical components" are, but generally, a proper multimeter's continuity function isn't enough to harm most things. A good meter will apply a small voltage through a moderate impedance, so the total power that the meter could deliver to the device under test is very small. Even if the resulting current and voltage is outside of the ...


9

If there is room, I like to put real test points (that you can clip an oscilloscope probe to) onto a board for any signals I might want to look at, plus all power rails. You can get them in either through-hole or SMT varieties. Both are around the same price (about 40 cents in single quantities). They can easily be left off (marked DNI/DNP) in production ...


9

This is more of a blog post, but here goes: If you write in C, you can compile your code and run it on your desktop. This won't test the low-level hardware drivers, but can test all the logic code. Recommendations on this approach: If you're on ARM, you can use the same compiler (gcc) for both purposes. Then any compiler-specific extensions will ...


9

I am choosing to answer this part of your question which has been neglected by other answers "Is there an easier way to test my battery's capacity?" Yes, you already have the means to test your battery capacity with the discharge function on your LiPo battery charger at 1A rate(follow mfr directions). Or just discharge at 1A rate and time it with a ...


9

They are called Test Point Terminals, believe it or not, and here is an example: http://uk.farnell.com/vero/20-313137/terminal-pcb-red-pk100/dp/8731144 Many people make them, in many different colours and shapes.


9

You have shorted the internal core voltage regulator to the external 3.3 volt supply. Pin 89 is VDDCORE VDDCORE pin is just an output for monitoring the internal voltage regulator. This is not an input for an external supply Unfortunately you have mistakenly connected this to the 3.3 volt rail. It's quite likely you have permanently damaged the chips,...


8

Vias take up space on at least two layers on the board. Test pads take up space on just one.


8

Put a maximum load on the power supply. Power resistors, home-made power resistors, incandescent lamps (for example car headlights for a 12V load). I use a couple electronic loads which can be programmed to draw a certain steady current, a constant power (negative resistance) or to simulate a given positive resistance. Many real loads are not constant - the ...


8

Unless you want to do your own S-Parameter de-embedding mathematics, you must fit a 50\$\Omega\$ connector to at least one end of the trace. You can either fit a connector to the other end, or a good quality 50\$\Omega\$ resistor. I tend to use 2 x 100\$\Omega\$ resistors in parallel for lower ground inductance. There are many connector styles to choose ...


8

Google for "dynamic braking resistor". They are not cheap, but they are available down to just an ohm or two and up to multi-kilowatts. They are basically large heaters, but the nice thing is that you can specify the resistance, current and power that you need.


8

Putting in those pads first time round is called DFM (Design For Manufacture). And it sounds like they're giving you a good price on the bed of nails. Either get this flow working (it's perfectly normal) or ask your next fab house if they have a flying probe tester in house. One way to economise is to use bed of nails ONLY for nets that don't already ...


8

A reason to do this would be to get a quicker assessment of the charge capacity at a constant 5A drain. Another may be because that more closely simulated the actual battery drain on the Llama farm 75 years ago. All batteries tend to have a characteristic open-circuit voltage to which they'll recover under no load. For some chemistries (NiCd, dry cells), ...


7

There is no non-destructive black-box test you can do on a battery to see whether it has any dangerous failure modes. You can test it for voltage, for capacity, for internal impedance, for in/out charge or energy efficiency, but you cannot test it for what it takes to blow it up without blowing it up. Amongst some hobbyists whose forums I follow, the advice ...


7

The answer to the question depends on where in the world you are located. Let us for discussion's sake assume Europe. The rest of the world seems to be accepting or even adapting to the European bureaucracy model, so it applies somewhat globally. It goes like this: The European Union has invented a system where the responsibility to know about every ...


7

You might use a load tester. These devices are designed for testing vehicle batteries and alternators and are intended to handle hundreds of amps in your voltage range. They're basically a big carbon pile resistor in a box with an ammeter and voltmeter. A 500A one can be had for about $50 (examples 1 2). Only problem is you'd be going much longer than ...


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