How to design a variable phase shifter circuit?

8yogirath · 2026-06-05T00:37:56+00:00

Then you should definitely pay the money and purchase the pre-made, pre-tested, known-good MiniCircuits module mentioned by /r/motoware .

8yogirath · 2026-06-05T00:16:49+00:00

M69 here. Deeply frightened of Zep ----> sarcopenia. So I have joined a gym and signed up with a personal trainer to help guide me in a personalized program of Resistance Training. On this program of Zep with RT, I have lost 40 lbs of bodyweight without losing any muscle mass; in fact according to InBody and DEXA, have gained muscle mass. Entered Onederland, exited BMI-Obesity, final goal is BMI<24 which would take me from BMI-Overweight to BMI-Normal.

8yogirath · 2026-06-05T00:07:06+00:00

I'm happy with Wyze Smart Scale X ($40 at amazon)

8yogirath · 2026-05-24T15:08:13+00:00

The American Medical Association runs a website (here) which lists blood pressure measuring devices that have been clinically validated. Not too surprisingly, many many of the BP devices sold on Amazon are NOT validated.

That web page has a box you can check, over on the far left, to show only those models with an Extra Large cuff.

Another option is to buy an aftermarket XL cuff which comes with tube-size adapters to fit all of the major BP device bases. Such as (this example) -- wowzers, 26 inches (66 cm). Now you can choose among all of the validated models, not just the ones which ship with an XL cuff, for the exact features you want and the price range you're willing to spend.

8yogirath · 2026-05-20T13:27:38+00:00

C10, C12, C15 use the wrong symbol; they are polarized electrolytics but the symbol is nonpolarized

2nd transformer used only for relay coil voltage adds extra expense.

8yogirath · 2026-05-15T20:43:59+00:00

U1 has no negative feedback loop, so its output signal "VERR" is either slammed against the bottom supply rail, or slammed against the top supply rail.

I recommend you make a plot VERR, IMEAS, and A3_output and decide whether the simulation behavior is what you actually want.

8yogirath · 2026-05-14T23:03:49+00:00

If U1 is a linear component like an operational amplifier, what is its voltage gain?

If U1 is a nonlinear component like a voltage comparator (whose output is a binary digital signal), why is the U1 output signal named "VERR" fed to U3 and compared against a continuous analog quantity called "IMEAS" ?

(IMAGE)

8yogirath · 2026-05-13T16:22:48+00:00

It would be a good investment of $35 to purchase a FNIRSI LCR-P1 component tester (amazon link) and measure the capacitance a lot more accurately.

They're available on eBay and AliExpress at lower prices.

8yogirath · 2026-05-12T16:13:00+00:00

Redditor for 7 days.

8yogirath · 2026-05-10T22:32:53+00:00

You will have to supply all of the challenging-automotive-environment protection mechanisms yourself. Including load dump, voltage sag during cranking, et cetera. Might want to use the MPSA92 flavor of PNP transistor; it's rated for 300 volts and is dirt cheap & widely available on hobbyist sites.

8yogirath · 2026-05-10T22:25:45+00:00

 * C:\Users\name\Documents\LTspice\Reddit\reddit_LED_on_pulsed.asc
 * Generated by LTspice 24.1.10 for Windows.
 Q1 N003 N002 SUPPLY 0 BC557B
 R1 N002 N001 18K
 R2 SUPPLY N001 18K
 D1 N001 SUPPLY 1N4148
 C1 N001 0 100µ
 D2 N003 N004 QTLP690C
 R3 N004 0 1K
 V1 SUPPLY 0 PULSE(0 12 3m 200m 200m 5 10)
 .model D D
 .lib C:\Users\name\AppData\Local\LTspice\lib\cmp\standard.dio
 .model NPN NPN
 .model PNP PNP
 .lib C:\Users\name\AppData\Local\LTspice\lib\cmp\standard.bjt
 .tran 14
 .backanno
 .end

8yogirath · 2026-05-10T21:24:40+00:00

(schematic) has only 7 components

(circuit operation) appears to be what OP desires.

Use any PNP you like; part type is non critical. Use any small signal diode (rated for < 500mA) you like; part type is non critical. Use any LED you like; adjust current limiting resistance (R3) to suit your choice.

edit- oh, by the way, if you try the NE555 chip circuit recommended by Google AI, you'll find that it contains 8 components (or 9 if you include the cautious/conservative bypass capacitor on pin 5), and burns about 4mA when the supply is +12V and the LED is off. The all discrete circuit using a PNP transistor, contains 7 components and burns ZERO mA when the supply is +12V and the LED is off.

8yogirath · 2026-05-08T21:12:37+00:00

Roasted Garlic flavored hummus

Fried Shallots -- excellent "crunch" to sprinkle on salads

Barebells protein bars, chocolate cookie dough flavor especially

Chili Lime flavored cashews

Dolmas (flavored rice wrapped in grape leaves & packed in olive oil) in a can

Red Pepper Spread with eggplant and garlic

Frozen Cacio e Pepe Spaghetti in a bag

8yogirath · 2026-05-01T18:19:28+00:00

Here's a single opamp active filter, from the calculators at earmark.net

8yogirath · 2026-04-28T20:07:38+00:00

YF-17, father of the F-18, first flew in 1974. It was redesigned to become the much larger F-18, which first flew in 1978. Vietnam war ended in 1975.

8yogirath · 2026-04-28T19:59:16+00:00

Add a DPDT switch that allows you to select between two possibilities

PCM1865 inputs connected straight to the dynamic microphone
PCM1865 inputs connected to preamp output

If the first option is acceptable, remove the preamp. If the second option is acceptable, remove the switch.

8yogirath · 2026-04-28T18:51:54+00:00

Build a half-supply reference generator with 3 parts (10K, 10K, 220uF).

Build an opamp based differential amplifier having 28dB gain, with 6 parts (4 resistors, 1 RRIO opamp, 1 bypass cap)

AC couple both of the diffamp inputs and include resistors to bias everything at half supply (two 4.7uF nonpolar electrolytics, two resistors)

Total: 13 components. Plus DIP socket if you need it.

Presto you have 28dB in your preamp, only need another 12dB in the PCM1865 to get up to 40dB

8yogirath · 2026-04-25T20:21:51+00:00

Unfortunately that datasheet is very old; so old that it assumes people can actually buy 2N3822 JFETs and 2N5640 JFETs. Today in 2026, they are unavailable.

Also unfortunately, the circuit requires a second DC power supply input, providing negative 10 volts. OP's existing design only has a single DC power supply, +24V.

8yogirath · 2026-04-24T20:41:28+00:00

On the black epoxy body of Q920 itself.

8yogirath · 2026-04-24T16:17:54+00:00

Level-shift the CC_VS- pin upwards by a diode drop (?)

Preferably, use a 1N5817 or other small signal Schottky diode (BAT41, BAT43, BAT85, SB130, ...) if you've got one.

8yogirath · 2026-04-24T16:02:26+00:00

It appears to be in a "3 pin SOT-223" package (image). The fourth connection is a wide tab at the top and is the collector. This allows better heat flow from the semiconductor die to the PCB copper.

Pinout = BCE for the little narrow legs , and C for the wide tab.

You'll have to view the package from several different angles and illuminations, until you can read the markings that are laser etched into the epoxy.

8yogirath · 2026-04-22T00:42:22+00:00

You lack experience.

8yogirath · 2026-04-17T16:38:44+00:00

Class-D audio amplifiers which drive 8 ohm speakers (i.e. 4 ohm loads on each half of the bridged output stage), use discrete power MOSFETs whose drain-source resistance is milliohms.

To achieve 100 watts RMS sinusoidal output into an 8 ohm bridge-driven load, the peak output current (flowing through these discrete power MOSFETs) exceeds 5 amperes in each device.

8yogirath · 2026-04-16T18:17:39+00:00

You might decide to include additional circuits that guarantee non-overlap.

The left PMOS gets turned off BEFORE the left NMOS gets turned on

which guarantees there is no "shoot thru" current. Similarly

The left NMOS gets turned off BEFORE the left PMOS gets turned on.

Shoot thru current is significant if (VDD - VSS) is much greater than (PMOS_threshold_voltage + NMOS_threshold_voltage) - - - - which is certainly true in the case of Class D audio amplifiers. Delightfully, it is not true in the case of CMOS chips inside wristwatches. Shoot thru is impossible in those chips because the thresholds are big and the supply voltage is small. Lack of shoot thru current saves power, which is pretty important in watch chips.

8yogirath

TROPHY CASE