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Hey friends,
I have a two daisy chained shift registers (74AHC595) which are controlled via an ESP32. I want to set one output to high at a time before switching to the next.
The code seems to work, but the outputs O_9 and O_10 are not staying high (zoom) after setting them, whereas all the other ones are working fine. This is the used code snipped:
pinMode(SHIFT_OUT_DATA, OUTPUT);
pinMode(SHIFT_OUT_CLK, OUTPUT);
pinMode(SHIFT_OUT_N_EN, OUTPUT);
pinMode(SHIFT_OUT_LATCH, OUTPUT);
digitalWrite(SHIFT_OUT_N_EN, LOW);
uint16_t input_bin = 0b1000000000000000;
for(int i=0; i<17; i++){
byte upper_byte = input_bin >> 8;
byte lower_byte = input_bin & 0x00FF;
digitalWrite(SHIFT_OUT_LATCH, LOW);
shiftDataOut(SHIFT_OUT_DATA, SHIFT_OUT_CLK, MSBFIRST, lower_byte);
shiftDataOut(SHIFT_OUT_DATA, SHIFT_OUT_CLK, MSBFIRST, upper_byte);
usleep(10);
digitalWrite(SHIFT_OUT_LATCH, HIGH);
delay(10)
input_bin = input_bin>>1;
}
Is there anything I'm doing wrong, or any idea on where the problem may lie? I've already tried looking for shorts and other error sources, but the design was manufactured on a PCB and no assembly issues are noticeable.
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I'm trying to build a esp8266 weather station and got some MCP1700-3302E to power the esp8266 from a lipo. But when I connect the lipo to the MCP1700 (looking at it flat spot at the front, ground left, Vin in the middle and Vout on the right) I get no output at Vout. I googled and could not find anything. I tested 5 different ones and it's the same for all of them. Could I just have a batch of broken ones? Edit: attached a picture of my very simple test setup Edit 2: I just connected three lipo directly to Vin, that seems to work without any problems (at least for a few days now)
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It's the handle of a water kettle. Behind the circuit board is nothing. There is also no other circuit board in the kettle. Is the yellow thing the beeper? Thanks for any help 🙏
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Hi, this post is structured similarly to r/PrintedCircuitBoard 's review request format. Since we don't have any PCB communities over here yet, I thought that this might fit in here and can maybe spark some friendly discussion.
This is a relay board controlling electrically driven windows and blinds. For this purpose it has some additional connectors to a weather station, interior sensors and an LCD screen.
It is replacing a ~20 year old board that has started to develop some annoying quirks. I've mostly copied what the original board did and adjusted it for the ESP32. This is not a production board and if all goes well, I will only ever assemble a single one of these.
The primary usage scenario is that the MCU will monitor the weather station and then actuate the motor groups (M1 - M6 connected on J3 - J8) to keep the indoors temperature and humidity in check.
At least during summer time the board will likely run 24/7 and will hopefully be used for a number of years. For maintenance reasons I've tried to keep it simple and the component count low.
Mains power is supplied from J1 and being fed to the motors via the relays. PS1 converts the line voltage to +5V DC for the relay coils and some auxiliary components. The switching regulator U2 steps that down to +3.3V for the MCU U1 and IO Expander U3.
The board size is mostly constrained by the preexisting mounting holes which gives me plenty of space to work with even with just a 2 layer board. The enclosure containing the mounts is installed indoors and is finger-pokey-tight.
Jumper JP1 allows me to supply the MCU devkit daughter board with +5V, should I ever replace it with a different one. Similarly J11 exists for future expansion.
J10 mounts another daughter board (not included in review) facilitating communications with the weather station. Should the station ever need to be replaced I can swap in a new, matching board.
There aren't any high-speed connections on the board. The fastest one is likely the SPI connection to the LCD controller but I can slow it down in firmware if necessary.
Regarding the DNP components: There are only 5 motors installed at the moment so I will cover the sixth slot with a piece of plastic for now. R1 and R2 will only be populated if the 10k pullup resistors integrated into the MCU are insufficient for typical baud rates.
While it is not the first board I've designed, it is the first one carrying mains power (European grid 230V@50Hz). I'm using 2 oz copper to accommodate the motor currents within reasonably wide traces.
In case anyone is interested, it will be running the ESPHome firmware to easily integrate with the Home-Assistant smart home solution. This also pushes firmware maintenance from me onto the ESPHome devs.
3D render from front (no 3D model for relays K** and MCU board; 3D model for J1 and J2 is a stand-in of same outer dimensions):
Orthographic view from front:
Schematic:
PCB All layers (For reference: thickest traces are 2.5 mm / ~98.4 mils; thinnest traces are 0.25 mm / ~9.84 mils):
PCB Front layers excluding Silkscreen:
PCB Back layers + Front Fab layer:
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Solution: @[email protected] has made some really insightful comments below, which are really useful. ~~If you just want the cap you can set the parametric searches for 660uF, or in September 2023 I've found that digikey stock(s/ed) chemi-con EKHJ451VSN661MA59M~~.
Update 2: Turns out that EKHJ451VSN661MA59M is not the ordering code you'll want. That would be EKHJ451LIN661MA59M which returns 0 results when you Google it, or maybe a single result in a few days linking to this thread. So it looks like you'd be better off just getting some 680uF with blade snapins instead and retrofitting the board if possible. Just make sure it can handle the ripple current. Always check ordering codes twice my friends!
Original post
I need help identifying the terminals on some strange caps found in an AC inverter main board. The reason I state the AC part, is that the only other mention I've found of this layout, was a question on digikeys forum regarding an AC inverter https://forum.digikey.com/t/can-t-find-the-right-terminals-for-a-capacitor/19332 The capacitor in question has the same measurements as the one in the link.
In my picture on the right you can see the layout of the terminals, there's room for three caps, but only two was mounted, hence the relatively clean pads. On the left is one of the two caps in question. It says nichicon LQ(K), 85°C. Nichicon has discontinued the LQ-series, and the datasheet doesn't mention a 660µF variant. I don't know what fujitsu did to get caps with capacitance outside the E24 series.
Question: What is the name of this type of terminals? And more importantly: where can you get 680µF 450V caps with them? I haven't found them on neither Farnell or RS-Online.
For the sake of people googling this in the future, the AC in question is a fujitsu AOYS09LDC and the board was marked K05CM-C-A(03).
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Disclaimer: this is not specifically for a commercial product, but various things I design sometimes get commercialized. I mention this so that you may decide whether you want to weigh in. If it's commercialized, I will probably make very little money but a bunch of university students may get a neat STEM program in the countryside :D
That out of the way, I've designed some boards for a Wi-Fi controlled robot with mechanum wheels. So 4 independent motor drivers, one for each wheel, allow omnidirectional motion. It's built around a Pi Pico W, 4 SOIC-8 9110S motor drivers, and some buck/boost converters to give the system a 5V and 12V line. It's very basic, mostly made to be cheap. Here's a photo:
Right now it just receives UDP communications (a little app written in Godot) and activates the motors in different combinations -- very "hello world". I'm planning to add some autonomy to move around pre-generated maps, solve mazes, and so on.
I have foolishly used 2-pin JST connectors for the motors, so using motors with rotary encoders would be a pain without ordering new boards. I'll probably fix that in a later board revision or just hack it in. Also the routing is sloppy and there's no ground plane. It works well enough for development and testing though :D
What I'm thinking about right now, is how to let the robot position itself in a room effectively and cheaply. I was thinking of adding either a full LiDAR or building a limited LiDAR out of a servo motor and two cheap laser ToF sensors -- e.g. one pointed forward, the other back, and I can sweep it 90 degrees. Since the LiDAR does not need to be fast or continuously sweep, I am leaning toward the latter approach.
Then the processing is handled remotely -- a server requests that the robot do a LiDAR sweep, the robot sends a minimal point cloud back to the server, which estimates the robot's current location and sends back some instructions to move in a direction for some distance -- probably this is where the lack of rotary encoders is going to hurt, but for now I'm planning on just pointing the forward laser ToF sensor towards a target and give the instruction "turn or move forward at static speed X until the sensor reads Y", which should be pretty easy for the MCU To handle.
I'm planning to control multiple robots from the same server. The robots don't need to be super fast.
What I'm currently wondering is whether my approach really needs rotary encoders in practice -- I've heard that mechanum wheels have high enough mechanical slippage that they end up inaccurate, and designers often add another set of unpowered wheels for position tracking anyway. I don't want to add more wheels in this way though.
On the other hand, it would probably be easier to tell the MCU to "move forward X rotary encoder pulses at a velocity defined by Y pulses per second, and then check position and correct at a lower speed" than to use a pure LiDAR approach (e.g. even if rotary encoders don't give me accurate position, on small time scales, they give me good feedback to control speed). I could possibly even send a fairly complex series of instructions in one go, making the communications efficient enough to eliminate a local server and control a ton of robots from a cloud VPS or whatever.
Anyone have some experience with encoders + mechanum wheels that can offer a few tips my way? At this stage the project doesn't have clear engineering goals and this is mostly an academic exercise. I've read that using a rigid chassis and minimizing the need for lateral motion can reduce slippage, reading through a few papers didn't get me any numerical indication of what to expect.
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Some years ago, before LEDs were a thing, I bought an Ultrafire WF-500 Flashlight that features a Xeon light bulb. As you might imagine the bulb reached its lifetime and burned away.
Now a replacement bulb is available here https://www.ebay.com/itm/321916301663 the thing is that it will cost me 35€ and for that price I could just buy a new LED flashlight.
Now I was considering trying to adapt a generic LED bulb like this one here https://www.aliexpress.com/item/1005002419159094.html?mp=1.
Anyone else with this model of flashlight succeed at a similar mod? Any LED bulb recommendations? Or... is there any other source for the original bulb at a lower cost?
Some photos:
- https://cdn.tcb13.com/2023/wf500-bulb.jpg
- https://cdn.tcb13.com/2023/wf500-bulb2.jpg
- https://cdn.tcb13.com/2023/wf500-bulb3.jpg
Thank you.
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Looking for some Guidance Finding a Power Supply for a CrocSee CRS-7A016 Micro Water Pump (specs in post).
(reddthat.com)
Hi all, I have a water pump connected to an adapter (pictured) but I am having trouble getting it to run using any of the cords I had on hand; it calls for using DC-only & 12V (between 9-14). I have tried Googling around & browsing Amazon but I'm a bit overwhelmed with options. Can anyone suggest an adapter that'll get this little guy pumping? Please forgive my naivety & TIA.
Also, I hope that it's kosher I ask here. If it's not, please let me know if there's a better place. Thanks again.
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I am powering a 5V microcontroller (arduino clone, atmega328p) using a 9V block and a buck converter. Now I want to let the microcontroller occasionally measure the battery voltage, so I can get an idea of how full it is.
My first idea was to use a simple voltage divider:
I've chosen the resistor values so that:
- the voltage at the measure output is
< 1.1V, to be able to use the 1.1V internal reference of the atmega's ADC R1 || R2 < 10kΩ, since the atmega datasheet says "The ADC is optimized for analog signals with an output impedance of approximately 10 kΩ or less"
This is great and all, but what bothers me is that this circuit will constantly draw ~100µA from the battery.
So, my next thought was to add a mosfet to the divider, to switch it on only while measuring:
This is obviously bad, because now when the mosfet is off, the ADC input sees the whole battery voltage.
To address that issue, I've added a second mosfet into the measure path:
This works, and it does not draw any current, except while measuring.
However, it's quite a few parts. So I'm curious if anyone has an idea how to do this with just a single mosfet. It seems to me like it should be possible, but I haven't figured out how.
Oh, and if I'm doing something stupid here, please tell me :)
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