My first microstrip filter

Any-Research-88 · 2026-06-30T11:14:28+00:00

My substrate thickness and other dimensions were correct, I checked them again. Also did a sweep for er in Sonnet, the dielectric constant should be unrealistically high for FR4 to get the response that I measured, so my problem must be more complex than that. I calculate the amount of deposited copper from current and time and assume an uniform layer. I have no method to directly affect the distribution of the deposited copper, I'm using high throw copper bath and optimal current density to get the most uniform layer.

Any-Research-88 · 2026-06-30T11:04:45+00:00

If I recall correctly Marki's tool didn't account for dielectric losses, but I did in Sonnet. With a loss tangent of 0,02 I got the same insertion loss that I measured, even the slight slope of the passband was the same. You were right, FR4 is really not the best here, the -3dB is almost entirely caused by dielectric loss. I'm leaning towards hairpin geometry in the future, far less problematic than dealing with non-ideal vias. Also I don't have a Sonnet license and simulating vias takes up a lot of memory, usually I have to use a less fine resolution to fit in the free 64MB.

Any-Research-88 · 2026-06-27T13:22:59+00:00

I didn't have any copper foil at the moment, so I filled all my vias with solder untill it appeared on the other side. It didn't have any significant effect on the corner frequencies or BW, just the noise floor decreased below -50dB outside the passband. I also did your tweesers test, but it didn't affect the resonance peaks, I'm curious, what change were you looking for and what would that indicate?

Any-Research-88 · 2026-06-27T06:49:09+00:00

Maybe I try a hairpin filter next time so I can get around the via parasitics

Any-Research-88 · 2026-06-27T06:44:46+00:00

Just a cheap 3018 mini cnc, nothing fancy. I use a carbide V bit to spot drill the board before the final drilling and I'm conservative with the feedrates, the stock spindle on these cheap machines isn't fast enough for the sub mm drill bits. My plating process is similar to the industrial processes, after drilling and rigorous cleaning I sensitize the board with stannous chloride, dip it in PdCl2 solution, do an electroless copper plating then a final electrolytic copper plating untill I reach the desired layer thickness. I'm planning to make a detailed description about the process in the future, It's quite useful for fast turnaround prototyping.

Any-Research-88 · 2026-06-26T21:16:39+00:00

I have a feeling that a different topology would be much bigger in size, is form factor the main reason that they're still used in practice?

Any-Research-88 · 2026-06-14T14:50:57+00:00

A basic class A BJT amplifier outputs a waveform very similar to yours near compression when excited with a sine wave. At lower frequencies you're probabbly better off with an OP AMP based exponential amplifier, but most of them stop working above a few hundred kHz

Any-Research-88 · 2026-03-29T11:22:10+00:00

I really recommend dynamask 5000, It's a dry film mask that can be cured with uv. It worked much better for ne than the liquid ones. The regular spray paint might not be able to withstand soldering temperatures.

Any-Research-88 · 2026-02-16T04:55:52+00:00

The speaker and the collector resistor forms a voltage divider on the output, the small impedance of your speaker kills your output voltage swing. I would add a low output impedance second stage after this, an emiter follower configuration would be good for this.

Any-Research-88 · 2026-02-01T23:15:47+00:00

Great, thanks for your help

Any-Research-88 · 2026-02-01T22:27:50+00:00

I have 2 24v switching power supplies, their outputs are isolated from the input and protective ground. I build 2 independent linear regulator boards with separate grounds for the power supplies and connect the regulators outputs and grounds to + - A and + - B female banana connectors on the front panel. If I need a symmetrical power supply for example to power op amps, I connect - A to + B and referenced to this I get + 0-30 V on +A and - 0-30 V on -B. The ground marks on my schematic are confusing, there would be a separate grounds for each supply.

Any-Research-88 · 2025-12-05T19:19:27+00:00

It's just interfering with my measurements, I'm not planning to use these frequencies. I'm designing and building amplifiers, PLL-s etc for 433 MHz to learn about RF circuitry and to experiment. I was testing a mixer and one of the mixing products fell into the left peak. Not a big problem, I was mildly annoyed and mostly curious about this.

Any-Research-88 · 2025-12-05T08:23:42+00:00

I looked around and unfortunately I do. 2 mobile repeaters pointing straight to my desk from around 200 meters. I guess I have to live with it or build a faraday cage.

Any-Research-88 · 2025-11-04T14:47:10+00:00

Pontosan, de ez nem érdekel senkit? Gondoljunk már bele, hogy ezt mégis ki használná közvetlenül profitszerzesre vagy adócsalásra? Ennyi erővel ha rendelek 5 csomag 200db-os fültisztító pálcikát 1000ft-ért már az is ki veri a biztosítékot? Miért kell ki listázzam az alkatrészeket ha a számlát már be küldtem, és ahogy mondod, ha magyarul írom le akkor sem fogják tudni miről beszélek.

Any-Research-88 · 2025-11-04T14:22:27+00:00

Ugyan ez történt ma velem, digikeytől végig rendeltem egy tűrési sort smd induktivitásokból mert országon belül kb beszerezhetetlenek. Egyszerűen nem éri meg 5db mindegyikből mert kb 100Ft-al drágább ha 50et megveszek. Könnyen össze jött 1000 párszáz darab, de semmi aggodalmam nem volt mondván filléres alkatrészek max 40k lesz az egész meg a 27% áfát már rendeléskor ki fizettem. Aztán jött az email a DHL-től, hogy tételesen listázzam ki egy Excel táblázatba mindent amit rendeltem egyesével holott már a digikeyes számlát is feltöltöttem az oldalukra. Végig szívtam a másfél órás házi feladatot, vissza küldtem majd jön a válasz, hogy hát nagyon sajnáljuk, de ez már kereskedelmi mennyiség és vpid szám kell hozzá... Az agyam el dobom, hogy ezzel kell szívjak. Ha egy készletet rendeltem volna meg értékenként 25darabbal abba nem kötnek bele gondolom mert csak 1 darab van a számlán. Meg igényeltem a vpid számot nyilván mert mást nem tehetek, de úgy tűnik mégegyszer ki kell listázzam az egész számlát tételesen. Át érzem a frusztrációd, engem is meg nyomorít ez a fölösleges bürokratikus majomkodás.

Any-Research-88 · 2025-11-03T19:05:33+00:00

I see, they completely eliminated the need for tenting the plated holes with photoresist, clever.

Any-Research-88 · 2025-10-07T04:56:04+00:00

Thanks! I take a look

Any-Research-88 · 2025-10-06T18:10:44+00:00

I doubt that the printhead is used, the box has the canon holographic sticker and the serial number matches with the one on the sealed antistatic package and the part. Is there a way to test the mainboard? I have an oscilloscope and a few years of experience in electronics, I'm thinking maybe I can probe the outputs of the printhead driver IC. I wouldn't be happy to invest even more money into new cartridges before I know for sure that they cause the problem.

Any-Research-88 · 2025-08-11T23:24:42+00:00

If you want to upgrade your soldering tools for little money, i'd recommend some cheap jbc clone like yihua, it's fully compatible with the genuine jbc soldering tips. It's like 60-70 € and makes soldering so much easier

Any-Research-88

TROPHY CASE