On some of the inexpensive Dell laptops they implement a hardware-lockout system intended to prevent you from using aftermarket charger bricks...

On some of the inexpensive Dell laptops they implement a hardware-lockout system intended to prevent you from using aftermarket charger bricks to charge the battery. The way they do this is there's a chip in the Dell charger that contains a unique identifier which a chip on the laptop mobo requests from it on startup over a one-wire interface. If on boot the BIOS can't confirm that the ...

I have a differential output from a fast CML flipflop, powered by +3 and ground, and want to drive another CML-input part. If the load gadget...

I have a differential output from a fast CML flipflop, powered by +3 and ground, and want to drive another CML-input part. If the load gadget was also powered from +3, I'd just connect them with a couple of 50 ohm traces. But the Vcc of the destination part could be anything from +3 to -2. I want full speed and DC coupling, so the ideal part to put in series with both runs is a battery ...

So I was out at UB, (picking up some stuff) I was talking with Bruce's* final grad student. He had some success biasing a resistive FIR...

So I was out at UB, (picking up some stuff) I was talking with Bruce's* final grad student. He had some success biasing a resistive FIR detector with a current source. The grey haired tech turned him onto an LM134. (A new IC for me too.) http://www.ti.com/lit/ds/symlink/lm134.pdf Apparently they are running it dry down at 1uA and either need more voltage or less current.** (Suppl...

https://www.studyfinds.org/fear-for-safety-every-day/ What's wrong with kids these days? Most have been super-protected children but are...

https://www.studyfinds.org/fear-for-safety-every-day/ What's wrong with kids these days? Most have been super-protected children but are afraid of life. Engineers have to THINK, blow things up, take calculated risks. Fear warps prudent judgement. I've had interns that were afraid to touch a board powered from 5 volts, or handle a 12 volt battery. And wanted eye protection and masks ...

I have a situation where I need to change a momentary switch to an on / off switch. This is ordinarily very easy using a JK Flip Flop, but there...

I have a situation where I need to change a momentary switch to an on / off switch. This is ordinarily very easy using a JK Flip Flop, but there is a twist. The device runs on a 6S Lithium battery, so the voltage will vary from about 18V to 25V or so. In addition, I need the power control circuit to use very little current - on the order of 100 uA - when off. It can use much mor

After using a pair of inverter/charger circuits as UPS units for some months I've become curious as to how the trigger decides when to switch...

After using a pair of inverter/charger circuits as UPS units for some months I've become curious as to how the trigger decides when to switch from line power to the battery and inverter. Supposedly they trigger on wrong voltage or frequency, but they do it in less than a half-cycle, so it seems to be more than a simple relay. A cursory web search found nothing but I don't know the proper...

Anybody know of a good source for handheld enclosures to fit a standard 16x2 line backlit LCD display? Preferably one that also has a 9-volt...

Anybody know of a good source for handheld enclosures to fit a standard 16x2 line backlit LCD display? Preferably one that also has a 9-volt battery compartment. Plastic is preferred. (Metal is also OK) And preferably one that comes complete with a bezel. This will be for a generic (temporary-use) handheld-type tester for something that runs on an RS-485 loop. So, a place to put QTY-(1...

Hi all I am playing around with a solar lamp, pretty simple like this https://www.pinterest.com/pin/540150549038731182/ However I do not...

Hi all I am playing around with a solar lamp, pretty simple like this https://www.pinterest.com/pin/540150549038731182/ However I do not (yet) have D2. D1 in my case is a Schottky 1N5818, and my battery 7.2V I am surprised how much reverse current I can get through the diode. Without the solar cell, it does not turn on. There is enough current through D1 to the transistor to turn the wh...

I have a little transistor radio that was drawing excessive power from the battery. It was about 125mA at 6 volts which is 10 times too much. I...

I have a little transistor radio that was drawing excessive power from the battery. It was about 125mA at 6 volts which is 10 times too much. I found I could bend the circuit board to eliminate the problem. So, I studied the thing for an hour or so and found the problem had something to do with the audio output transformer. This radio uses an input and output transformer in a push pull a...

Flyguy has this nasty habit of claiming that I want to fire bomb my own country. There was a thread about electric aircraft, and Flyguy came up...

Flyguy has this nasty habit of claiming that I want to fire bomb my own country. There was a thread about electric aircraft, and Flyguy came up with an accident report about an ultralight aircraft that had caught on fire. essentially because it's owner had abused the batteries. I suggested that it would make sense to dump an overheating battery pack before it caught on fire. Flyguy over-s...

I know many engineers here work on cars, so ... I am debugging my wife's Lexus ES300. The problem is that the OEM alternators (original and...

I know many engineers here work on cars, so ... I am debugging my wife's Lexus ES300. The problem is that the OEM alternators (original and replacements) are not charging at idle. At idle speed, the alternator put out 8V to 10V, which is insufficient to charge the battery. At high speed, it does put out 14V. People suggested speeding it up by changing the front pulley (65mm) to a small...

Recent experience (first) with a Lenovo Tab 8 had me scratching my head. It's USB (~charging) port could communicate with a PC for file...

Recent experience (first) with a Lenovo Tab 8 had me scratching my head. It's USB (~charging) port could communicate with a PC for file transfer, but couldn't read a memory stick. This with all the recommended OTG cabling. Why would you stick a communicative USB port on a battery-operated device and then restrict it from acting as a USB host? Is this normal? Is this sane? ...

I'm working on a battery-powered bit of kit for a client. His old system was powered by lead-acid batteries, and while we don't feel a need to...

I'm working on a battery-powered bit of kit for a client. His old system was powered by lead-acid batteries, and while we don't feel a need to retain continuity for continuities sake, we should think before we step away from what's been done. Does anyone happen to know what the deal is with RoHS and lead-acid batteries? Do you get a pass on that, or is there some well-structured way...

For a hobby project, I've found the perfect part for converting battery power to a very low current (2 ma at most) 28V power supply. And that...

For a hobby project, I've found the perfect part for converting battery power to a very low current (2 ma at most) 28V power supply. And that is the Linear Technologies LT8410-1 "Ultralow Power Boost Converter". The problem is that the only package available is a tiny surface mount chip that's 2 x 2 millimeters, which effectively makes it impossible to deal with using a soldering iron....

Seems to really hate some Sandy Bridge/Ivy Bridge machines, I use a Fujitsu Lifebook which has some nice features like a VGA output...

Seems to really hate some Sandy Bridge/Ivy Bridge machines, I use a Fujitsu Lifebook which has some nice features like a VGA output (for connecting to older projectors) and easily-replaceable battery and

OK..... So ahm happier'n'a alcoholic workin the night shift in a Jack Daniels distillery.... with my 400# deep cycle battery, 1500 W...

OK..... So ahm happier'n'a alcoholic workin the night shift in a Jack Daniels distillery.... with my 400# deep cycle battery, 1500 W inverter (sitting in the back seat of m'truck), and my brand new blue electric blankey-poo..... Now I can curl up in a fetal position -- in m'truck -- in compleat toasty comfort..... Now, don't ax me WHY I gotta curl up in a fetal position -- in m'tr...

Here's something that may interest some folks here. I just got my new Tonghui TH2821A LCR Meter, and I'm starting to become quite impressed....

Here's something that may interest some folks here. I just got my new Tonghui TH2821A LCR Meter, and I'm starting to become quite impressed. After some screwups due to a discharged internal battery and not reading the instructions, it is starting to give some really impressive results. 5 digits resolution on 1000uf caps, 4 digits on iron-core inductor, miscellaneous resolution on 30k...

GM advices not to charge more than 90%, and discharge less than 70 miles. So, effective range of 60 miles? Not much more than my 50 miles Leaf. ...

GM advices not to charge more than 90%, and discharge less than 70 miles. So, effective range of 60 miles? Not much more than my 50 miles Leaf. At least, Leaf batteries don't catch on fire. Leaf batteries are inefficient but over-engineered. https://www.cnbc.com/2021/07/23/gm-issues-second-recall-of-chevy-bolt-evs-after-vehicles-catch-f ire.html

This is an about -30 dBu sine wave being amplified to about 0dBu by the triode section of a Sylvania 12EC8 triode/pentode "space charge" tube....

This is an about -30 dBu sine wave being amplified to about 0dBu by the triode section of a Sylvania 12EC8 triode/pentode "space charge" tube. The plate load is a single transistor gyrator/constant current source. Plate and heater currents are being supplied by a "China Special" boost converter module that's stepping up a 4 "C" cell battery pack. http://tinyurl.com/zeegduc Yick. Lots...

I just installed a quartz battery movement into a wall clock that once had a mechanical movement. I lost the pendulum capability and I'd like...

I just installed a quartz battery movement into a wall clock that once had a mechanical movement. I lost the pendulum capability and I'd like to find a simple circuit that would move the pendulum with the same speed as in a normal clock. I'd like to use the same pendulum the clock used before I replaced the movement, which is 3" diameter bob and 12" long. The circuit would be best pow...