hybridfree/eevblog-posts huggingface dataset:
DIY Cellular Car Starter Confusion - Page 1
Forum section: electronics / beginners

author: Calvin_Skinn
author_rank: Contributor
timestamp: January 18, 2016, 04:41:42 am
content: I am working on a car starter using a cell phone, arduino, and relay board. Pretty standard, but I'm trying to work out a bug. To end the call I have to activate the phone's end button. I had it wired up, but the button uses some different signal I guess and I'm not able to trigger it directly with the Arduino. When I give ground it to the arduino or even connect it to a multi-meter it imediately shuts off without any visual cue. All I am able to do is connect the two wires which works as it should. I was thinking of using a semi conductor as switch that I can control with the arduino. Any help is appreciated thanks.Subnote: Does anyone know of a good place to get a signal from the car to stop the ignition sequence, I live in a fluctuating climate and the time it takes for the engine to start running varies by up to 3 seconds; I can't really rely on a set time in the code.

author: Brumby
author_rank: Unknown
timestamp: January 18, 2016, 04:57:51 am
content: About the phone - I have no idea.But if your second question is about knowing when to stop cranking the engine because it has 'fired' and is running - the conceptual answer is easy. Pick up the vehicle's tachometer signal. The RPM at crank is a lot less than the RPM at idle - especially if you have automatic choke for cold starting. You'll soon work out a threshold to indicate when the car is running.Finding the tachometer signal shouldn't be too hard, but if you have any difficulty - you can use any source of pulses that are proportional to the engine's speed - such as ignition pulses for the spark plugs - on the low voltage side (with care about back EMF)

author: sleemanj
author_rank: Super Contributor
timestamp: January 18, 2016, 07:07:48 am
content: Well that doesn't look like an IED trigger at all....If connecting the two wires works then just use a small relay to connect the two wires, problem solved.Brumby has you sorted on the start detection, alternatively use vibration.
DIY curent probe? - Page 1
Forum section: electronics / beginners

author: Ahax
author_rank: Newbie
timestamp: June 18, 2025, 03:48:40 pm
content: Hello.I'm just wondering if I could use two normal scope probes to monitor the current? I tested it on a device but have no idea if the waveform I get is correct. I used a shunt resistor and connected one probe on one side and the other one on the other side of the shunt, Then I combined the channels and inverted the one with the lower voltage. I got a waveform that looks like it could be the actual current. I'm not looking for a correct amplitude just the correct waveform. Did anybody do that before? Any insight on the matter?Ahax

author: ledtester
author_rank: Super Contributor
timestamp: June 18, 2025, 04:28:28 pm
content: This video starting at 1:00:#855 Basics: Measure Current with an Oscilloscope -- IMSAI Guyhttps://youtu.be/JSBiIT3iljw?t=1m

author: Ahax
author_rank: Newbie
timestamp: June 18, 2025, 04:49:12 pm
content: Thank you

author: PGPG
author_rank: Frequent Contributor
timestamp: June 18, 2025, 05:49:03 pm
content: I sometimes measure the supply current with one probe at the resistor inserted between (-) supply (=probe GND) and (-) of supplied device (probe pin).

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: June 18, 2025, 06:24:47 pm
content: In the end, most devices including multimeters measure the voltage drop over a known resistor. If the resistor is close enough to an ideal resistor, the voltage drop and current have a linear relationship (Ohm's law).Then again, while using two probes and a math function will work, the resolution usually won't be great. Typically, you don't want a very large voltage drop over the resistor, so the resistance has to be low.Low voltage drop means small difference between the two signals, i.e. the difference might be much smaller than the absolute value of the two signals. If the absolute level of the two signals is using e.g. the 8bit resolution of a typical scope completely, and the voltage difference is a tenth of the absolute voltage, only 4-5 bits of the 8bit resolution remain. If the ratio is even worse, the resolution of the measured difference is even worse.There are specialized differential amplifiers for current measurement though (e.g. INA169, INA219, INA226).

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: June 18, 2025, 07:49:40 pm
content: When you mention: waveform, do you actually mean a switching waveform? I. E. The drain current of a SMPS’s Mosfet?The dv/dt is usually so large in those nodes, that noise will be injected, distorting the actual waveform.
DIY Current Limiter - Page 1
Forum section: electronics / beginners

author: peps1
author_rank: Regular Contributor
timestamp: November 26, 2013, 04:38:26 pm
content: Hey guysSaw this video on youtube of a Home made Current Limiter for working on Amps using just a 250w bulb, and was wondering if my little diagram below was the right way to wire for the UK? (Mains power scares the hell out of me!)

author: Dave
author_rank: Super Contributor
timestamp: November 26, 2013, 05:12:12 pm
content: Yes, you can use the same circuit in UK.There is no reason to be afraid of mains, just make sure that the wiring is done neatly and everything is well insulated. Check your connections with a multimeter before plugging it in.One thing I do not understand, is how the heck can one make a 9 minute video about something so trivial. Everything could be described in a minute, two tops.

author: peps1
author_rank: Regular Contributor
timestamp: November 26, 2013, 05:23:27 pm
content: Thanks Dave!Quote from: Dave on November 26, 2013, 05:12:12 pmThen you really won't like the rest of his videos

author: rr100
author_rank: Frequent Contributor
timestamp: November 26, 2013, 06:02:15 pm
content: I would strongly discourage anybody from using a bulb as a fuse. If you want to use a fuse, just use a fuse. Smaller and smaller chances to blow up in your face. Neither one will actually be fast enough to protect your mosfets in case you're doing the wrong thing but is better to know the risks than to just do stupid things thinking you're protected.

author: Excavatoree
author_rank: Frequent Contributor
timestamp: November 26, 2013, 07:18:27 pm
content: Quote from: rr100 on November 26, 2013, 06:02:15 pmI thought the whole point of the series light bulb was not to have the light bulb act as a fuse, but to take advantage of the lower cold filament resistance, and higher hot filament resistance. Yes, the effect can be too slow to protect semiconductors, but it will protect. If the current remains low, the bulb offers a negligible resistance. If a fault causes the current to increase, the bulb's resistance increases, thus limiting current.I believe some oscillators use light bulbs to exploit this effect.

author: Simon
author_rank: Unknown
timestamp: November 26, 2013, 07:29:51 pm
content: Quote from: Dave on November 26, 2013, 05:12:12 pmquite, I got board, I know that the practical electronics magazines i used to buy in italy often showed a 12v battery being charged via a 12V 5W bulb
DIY DC power supply kits? - Page 1
Forum section: electronics / beginners

author: wanaride
author_rank: Newbie
timestamp: June 07, 2016, 12:56:19 am
content: I enjoyed Dave's video about how to equip a "not half-ass" electronics lab. He showed many DC power supplies that he assembled and suggested others do the same. I'm searching for ready-to-assemble DC power supply kits (0-15V, 0-1A, current limit, dual tracking, etc) but am having a hard time finding them. I thought I would find a kitted product that required the user to solder everything together, and place the results in a provided enclosure. What I have found thus far are either (1) off-the-shelf completely assembled units, (2) small PCB kits made for attaching to a protoboard, or (3) project "ideas" on forums.I've looked at Sparkfun, Adafruit, Jameco, Nuts and Volts, and probably others I'm forgetting. I also looked at the "Silicon Chip" website Dave mentions, but I didn't see any such kits there.Do these "ready-to-assemble" kits exist, and if so, where can I find them?What did you do for your first DC bench top power supply? Buy off-the-shelf? Assemble a kit? Design and build from scratch?

author: klunkerbus
author_rank: Unknown
timestamp: June 07, 2016, 01:37:12 am
content: Someone pointed out this kit in a similar thread a while back -http://www.elenco.com/product/productdetails/power_supply=ODU=/same_as_xp720_in_kit_form=NTc4EDIT: likely not exactly what you are looking for, but unit-level kits are pretty rare these days. One of my first power supplies was a Heathkit IP-18 that provides 0-18V at about 500 mA. I built it about 1977, and still frequently use it as my go-to supply for testing LEDs, etc.EDIT 2: Actually, I've done just fine with electronics as a serious hobby without any of the whiz-bang benchtop supplies. I suppose it depends what you plan to do.

author: RobertHolcombe
author_rank: Frequent Contributor
timestamp: June 07, 2016, 03:52:51 am
content: I bought a Silicon Chip kit from Altronics (Australia) a few years ago;http://www.altronics.com.au/p/k3218-dual-tracking-0-19v-power-supply-kit/http://www.siliconchip.com.au/Issue/2010/June/Dual-Tracking+%C2%B119V+Power+Supply,+Pt.1It is rather expensive as a kit, but the PCB patterns/panel artwork are available to DIY
DIY Desoldering Tool Using Compressed Air / Ventura? - Page 1
Forum section: electronics / beginners

author: GrievousAngel
author_rank: Contributor
timestamp: December 01, 2024, 12:11:58 am
content: Many of the more expensive desoldering tools use positive compressed air applied to a ventura. One of the main advantages of using compressed air verses a vacuum pump is the comporessed is in a accumulator (~80 psi at low flow rates) waiting for a sol valve to shift. All this offers a near instantaneous vacuum to lift the molten solder up and away! While the vacuum pump has a significant rise time given the pump motor starts from an off state, i.e., zero vacuum pressure since no accumulator is present.You locate an inexpensive desoldering iron (~ $16 - $20) with a 'piggy-back' container to hold the removed solder. Some use a flexible ball that you squeeze & release. The vacuum hose would replace the squeeze ball in this example.If the vacuum pressure & flow rate was larger, the typical clogging and frequent cleaning would decreased significantly.Has anyone tried this approach to desoldering? Any other suggestions?Later, Billy

author: Andy Chee
author_rank: Super Contributor
timestamp: December 01, 2024, 02:15:09 am
content: I think poor desoldering is due to lack of heat, not lack of suction.

author: johansen
author_rank: Super Contributor
timestamp: December 01, 2024, 03:58:00 am
content: I desolder lots of crap by using a small tube and blowing the solder out of the joint.

author: Analog Kid
author_rank: Super Contributor
timestamp: December 01, 2024, 05:02:12 am
content: How 'bout a combination soldering iron/airbrush setup of some kind? I have a small compressor that I use with my airbrush; maybe could rig it up with a nozzle and a small valve placed near the soldering iron tip to just blow the crap away. (I've done that by just blowing with my mouth, but it's not very aim-able or controllable.)

author: Xena E
author_rank: Frequent Contributor
timestamp: December 01, 2024, 10:20:32 am
content: Quote from: johansen on December 01, 2024, 03:58:00 amGreat way to reclaim components.Bad way to repair a board. Solder particles and dust get under components, between leads, and into switches/pots.

author: Terry Bites
author_rank: Super Contributor
timestamp: December 01, 2024, 03:06:03 pm
content: I once toyed with the idea of converting a foot pump into a vacuum source. Heat and stomp.Anger out, solder out. Win win.
DIY FM Radio running off solar power - Page 1
Forum section: electronics / beginners

author: willbanks
author_rank: Contributor
timestamp: July 16, 2017, 12:25:28 am
content: Hello, I finished a schematic for an FM Radio that runs off of a 12V, 6W solar panel. Something like thishttps://goo.gl/TNsBNGHow would I go about figuring out the maximum distance that the antenna would be able to pick up? Is there a way to boost the distance without increasing the length of the antenna?

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 16, 2017, 01:06:32 am
content: By "FM" do we assume you are talking about the broadcast radio (88-108MHz in North America)?The distance or "range" of reception at those higher frequencies is rather dependent on the efficiency of the antenna.A random length of wire will not be as efficient as a dipole or a directional antenna like a Yagi or a log-periodic, etc.It is also affected by the sensitivity of your receiver, which you can increase with extra RF gain at the input. And, of course it also depends on the radiating power and distance of the radio transmitters.And even a simple piece of wire (or a "whip" antenna) will have better efficiency when the length is adjusted according to the frequency of interest. For example 1/4 wavelength is a popular length. For example the wavelength of 100 MHz is 3m. So 1/4 wavelength would be 750cm.Is this intended for portable use? or for fixed installation (where you could deploy a more efficient antenna)?

author: willbanks
author_rank: Contributor
timestamp: July 16, 2017, 02:09:39 am
content: yes north american. its gonna be used for portable use. so is the efficiency of the antenna based off of how good it actually is or the circuit itself?(also, this project is more for fun so I can learn more about electronics so the quality of the output doesnt have to be super good)

author: Red Squirrel
author_rank: Super Contributor
timestamp: July 16, 2017, 02:43:56 am
content: As far as power goes not much depends on that as far as a receiver. It's the transmitter doing all of the work, power wise. But as mentioned the antenna's design can dictate range, along with other things such as how high you mount it or if there's any pre amp, which I suppose would use a bit of extra power. Suppose a good tuner MAY use more power than a less good one but probably negligible.For a solar setup I would look at a car radio as it's already made to run on 12v and it will have a decent tuner. Easy to find 12v stuff as far as solar goes. Small charge controllers, batteries, etc. I would try to aim for like 30w solar though, 6w is kinda low, as you won't always get that rating. That rating is pretty much perfect conditions.
DIY heat pad?  - Page 1
Forum section: electronics / beginners

author: peps1
author_rank: Regular Contributor
timestamp: April 18, 2015, 01:47:43 am
content: Hello guys,I'm in the process of making a magnetic stir plate for mixing liquids, and would really like to add a heating plate.I was wondering if I could get some suggestions of how best to tackle this?Ideally want to power <12v, and only need MAX temps of 60°C for my application.Assuming some for of resistive element is going to be the easiest approach, but etch my own element on FR-4 copper clad, use resistors like the cheap USB mug warmers, silicone rubber heating pad

author: BradC
author_rank: Super Contributor
timestamp: April 18, 2015, 09:38:29 am
content: Quote from: evb149 on April 18, 2015, 03:27:37 amThis is what I did. A sunbeam aluminium electric frypan on a base with a motor under it and samarium cobalt magnets (I want in excess of 200C with the hotplate and neodymium just could not keep up). For your purposes, something similar with an old HDD magnet glued to the top of an 80mm PC fan would do the job. Mine worked great up until I started asking it to do in excess of 150C when the magnet demagnetized and the fan melted.

author: peps1
author_rank: Regular Contributor
timestamp: April 18, 2015, 04:52:20 pm
content: Quote from: evb149 on April 18, 2015, 03:27:37 amIt looks like a small 24/12V Kapton foil heater is the best option to me.What is the cheapest/easiest what to power/control foil heater?
DIY hydrophone build question - Page 1
Forum section: electronics / beginners

author: alexander_
author_rank: Newbie
timestamp: November 21, 2024, 04:32:46 pm
content: HI all. I'm somewhat experienced in coding but rather new to ee. I'm in the middle of a diy hydrophone project and getting stuck.The project:A DIY hydrophone which sends an analog signal to a raspberry pi 4. I'm building my own hydrophone sensor using a piezo cylinder taking inspiration from this project:https://www.instructables.com/The-Gladys-Hydrophone/Where as the model project is trying to record audio, I'm merely trying to detect the presence of a signal. If I can read voltage off the piezo, run an FFT on the signal, and compute the power spectral density of the frequencies I care about, this would be success.What I've tried:ADS1115 analog digital converterPiezo Ceramic Cylinderhttps://www.steminc.com/PZT/en/piezo-ceramic-cylinder-26x22x13mm-43-khzI have positive and negative leads coming from the piezo cylinder to a breadboard. A 1M ohm resistor between the piezo V+ and the ADS1115 is meant to match the impedance of the piezo cylinder. The ADS1115 is connected to a raspberry pi 4 via i2c. I have a script that continuously reads the voltage off the ADS1115 channel, performs an FFT on it, and displays the results in a graph. I would expect to see SOME kind of signal response with this configuration. However, when I run the script to read the pin, the FFT looks no different than if I leave the ADS1115 channel floating (ie, I unplug the hydrophone sensor). Even if I move the sensor around, lightly tap it, put an electric razor right next to it, squeeze it, the FFT always looks the same. There is a large spike near 0Hz, presumably DC offset, and a handful of small voltage spikes up to 450Hz.As I said, I'm new to electronic engineering - I don't even know enough to know how to diagnose the issue. The only thing I can thing to do is:- incorporate a rail to rail op amp as a unity gain buffer- add coupling capacitor to get rid of dc offset - this is necessary but I don't think its causing the issue outlined above- swap out ADS1115 for MCP3008 due to its much higher sample rate which would allow a wider FFTIf anyone has and rudder steers for me I would certainly appreciate it.

author: indeterminate
author_rank: Regular Contributor
timestamp: November 21, 2024, 09:09:58 pm
content: You need to amplify the signal from the piezohave a read of the linked doc's on the piezo www pagefrom the third docThe pre-amplifier must amplify signals around the transducer’s resonancefrequency (40kHz) and filter out all other frequencies• The pre-amplifier must provide high gain to pick up signals as small as acouple hundred microVolts
DIY...ish Bluetooth Mic - Page 1
Forum section: electronics / beginners

author: skillz21
author_rank: Frequent Contributor
timestamp: October 08, 2016, 11:19:29 am
content: Hi guys!I want to makethis, wireless/bluetooth withthis. is it possible to do this? also, can i couple two of the recievers/transmitters up so that i basically get a wireless audio... link? (i don,t think its possible, just wondering).Thanx!ps.fast responses appreciated

author: deephaven
author_rank: Frequent Contributor
timestamp: October 08, 2016, 11:23:28 am
content: Check signal levels, you might need an amplifier between the two.

author: skillz21
author_rank: Frequent Contributor
timestamp: October 08, 2016, 11:27:08 am
content: Quote from: deephaven on October 08, 2016, 11:23:28 ambetween the mic and the transmitter? How powerful would it need to be?

author: deephaven
author_rank: Frequent Contributor
timestamp: October 09, 2016, 03:45:02 pm
content: The spec's aren't too clear, but you might be able to get away with a direct connection. If you don't mind taking a risk, you could always try getting them and see if they work together. If you then need a bit more gain, you could get something later.
DIY JBC T245 station sanity check - Page 1
Forum section: electronics / beginners

author: jayy15x
author_rank: Newbie
timestamp: August 13, 2020, 10:54:40 am
content: Hi there, this marks my first post here. I started this project after coming across the videos by GreatScott and Marco Reps regarding DIYing stations for JBC soldering handles/cartridges.Ive finished the schematic and PCB as shown below, but I keep having this feeling that i've connected something wrong, and i'd rather not find out by blowing up an arduino/components/the not cheap T245 handle and cartridges. If anyone would mind quickly skimming through the schematic, particularly where the iron connects to the transformer, that would be much appreciated.The digital part of the schematic is omitted, i've got that down I think.I plan on powering the heater using a 100VA 2x12V toroidal transformer with the 2 secondary windings in series for 24V, this one:https://www.antekinc.com/as-1212-100va-12v-transformer/Will I be getting the most out of the C245 cartridges using this? Im not sure if I can use a 200VA transformer.

author: ledtester
author_rank: Super Contributor
timestamp: August 14, 2020, 02:14:20 pm
content: I would "unit test" your design as much as possible. This means isolating subcircuits and performing tests on them to verify their behavior.Some testing ideas:- does the zero-cross detector work? Some scopes allow you to trigger on the AC power line, and this can be used to determine when in the mains cycle your zero-cross detector is actually firing.- write an arduino program to control the intensity of a low-voltage light bulb through the IRON_AD control line; the light bulb will give you visual feedback of the amount of current you are feeding it.- write a program just to read the thermocouple and spit out the results to the serial console, for instance- use the least amount of power you need to perform these tests. 100VA is a lot of power. By comparison, the TS80 only uses 18W max and the TS80P only 30W. Find a lower power transformer for testing.These kinds of tests will build up your confidence that you've got things wired up correctly and you won't blow anything up.
DIY Label Rewinder - Page 1
Forum section: electronics / beginners

author: mariopaint
author_rank: Newbie
timestamp: November 09, 2014, 11:50:29 pm
content: I am thinking of building a label rewinder as 'commercial' units seem to be highly overpriced.I am using a dymo label writer to print labels and was thinking if I was to have an empty spool and a small motor attached this could be achieved quite easily.Would it be feasible to attach a pot to a 12v dc motor to adjust the speed?Also if anyone could suggest a suitable motor I would be most grateful.Thanks in advance.
DIY milliohm shunts - Page 1
Forum section: electronics / beginners

author: ledtester
author_rank: Super Contributor
timestamp: June 23, 2019, 04:00:56 pm
content: I'm interested in making an ~10 mOhm current sense shunt, but if I made it out of 20 AWG copper it would be about a foot long.The shunts you see in multimeters and digital panel meters are only an inch or two long. What kind of wire are they using???

author: Kleinstein
author_rank: Super Contributor
timestamp: June 23, 2019, 04:11:09 pm
content: Low ohms shunts are often made form a alloy called Manganin. Due to the alloying elements it has a considerably higher resistance than pure copper.Pure copper does not work well for a 2 nd reason: the resistance changes quite a lot with temperature (some 3500 ppm/K), the special resistor alloys have a much more stable resistance (often < 100 ppm/K, good ones < 10 ppm/K).For a DIY replacement one could use stainless steel - it has a relatively low TC. However soldering is not easy and needs special flux. Brass is also considerably better than copper, but the TC is not as low as with stainless.

author: Brutte
author_rank: Frequent Contributor
timestamp: June 23, 2019, 05:21:13 pm
content: There is alsoconstantanalloy.Definitely, copper is not suitable.There are 10m SMD resistors available, 100ppm are not that expensive.With 1W resistor you can get as high as 10A.

author: HighVoltage
author_rank: Super Contributor
timestamp: June 23, 2019, 05:50:03 pm
content: Look for Manganin resistors by Isabellenhütte (Germany) they are reasonable in price and very good and you can find good datasheets on them.

author: Bud
author_rank: Super Contributor
timestamp: June 23, 2019, 07:25:55 pm
content: "Resistance wire" on eBay or Amazon.

author: Seekonk
author_rank: Super Contributor
timestamp: June 23, 2019, 07:46:35 pm
content: Don't know your exact requirements. The steel strapping for hanging duct work with all the holes in it works. The large surface area keeps the heat down and has a place to bolt leads.

author: GerryR
author_rank: Frequent Contributor
timestamp: June 23, 2019, 07:52:37 pm
content: You can buy some .01 ohm 1% 50W resistors; the ones I have were made by Dale. We used them for motor current monitoring.

author: bob91343
author_rank: Super Contributor
timestamp: June 23, 2019, 08:19:55 pm
content: There is another consideration. The thermal emf between the resistor itself and the rest of the circuit can cause erroneous readings. It's desirable to make sure the ends of the element are at the same temperature. That means they should be supported as similarly as possible both physically and thermally.When dealing with millivolts, the thermal effects can really louse up a measurement. If the signal you are measuring is ac, the effects will cancel and you don't have to worry as much. But for dc measurements it can be an issue.
DIY Nanoleaf Linker Cord - Page 1
Forum section: electronics / beginners

author: Mastsarm
author_rank: Newbie
timestamp: February 25, 2018, 11:07:06 pm
content: Good Afternoon Electronic Gods,I recently acquired a set of nanoleaf panels and realized you must have a lot of panels to go somewhere, is there another way?Could one make a cord with linker ends from a usb cable or cat5 cable to connect the circuit and how would you do this? I am out of my area of expertise here!Much appreciated,Sam

author: Mastsarm
author_rank: Newbie
timestamp: February 26, 2018, 12:34:29 am
content: Here is a pic of the cord and linker

author: Mastsarm
author_rank: Newbie
timestamp: February 26, 2018, 12:47:56 am
content: wide look at the female housing
DIY nvg has either DVR working or IR-LEDs working - Page 1
Forum section: electronics / beginners

author: sackkrabbe
author_rank: Newbie
timestamp: October 15, 2025, 09:43:09 pm
content: I have built a DIY NVG with an night eagle 3 v2 as camera, a runcam mini DVR, a near eye display(https://de.aliexpress.com/item/1005008367358926.html?algo_exp_id=f437b0ea-66ce-44cb-8a51-eba131d85cdc&pdp_ext_f=%7B%22order%22%3A%22-1%22%7D&utparam-url=scene%3Aimage_search%7Cquery_from%3Apc_web_image_search)and four IR LEDs put in a series I stole from a old surveillance camera. This is powered by 2 9V block batteries put in parallel and converted to 5V with a TR10S05 from XP Power.When I first soldered everything together it worked well except for the DVR but it transmitted the video signal and electricity to the camera, as it is mounted directly behind the camera. After leaving the system running for about an hour the DVR came to life, but the LEDs only flicker a short amount of time before going off completely. Also the Display is not turning on, but this is probably because it ran for an hour.
DIY PCB Making for MSOP-12 SMD - Page 1
Forum section: electronics / beginners

author: brenesrob
author_rank: Newbie
timestamp: August 22, 2012, 03:49:59 am
content: Hey there,First of all I'd like to thank everyone that has been helping me out with my projects here on the EEVblog forum.Second, I designed a circuit and a PCB layout that uses a chip in an MSOP-12 package that includes a GND pad underneath of it. Due to the lack of manufacturers in my area I wanted to make my own PCB using the photoresist method, however, I am worried that I won't be able to get the traces small enough using this method for the MSOP package.Therefore, I was wondering, has anyone had success making their own PCBs with such small traces? Is the photoresist method the best way for this? If not, then do you solely recommend a fab house for these types of prototypes?Thanks in advance,Roberto

author: flolic
author_rank: Frequent Contributor
timestamp: August 22, 2012, 06:45:38 am
content: Quote from: brenesrob on August 22, 2012, 03:49:59 amNo problem at all using photoresist method

author: Psi
author_rank: Super Contributor
timestamp: August 22, 2012, 07:41:02 am
content: I've never used the photoresist method but I have made fine pitch TQFP pads using the toner transfer method.I'm not sure if the same thing will apply to you but the key i found was to oversize all tiny pads because they always over etched. This is because the etchant will eat sideways on a track as well as downwards. If the track is thick you dont notice as the percentage lost is tiny. But for small tracks this can become quite significant.eg a row of 4 correct pads might be like this#### #### #### ######## #### #### ######## #### #### ######## #### #### ####but it would end up like this after etching## ## ## #### ## ## #### ## ## #### ## ## ##So i just made them like this to start with##### ##### ##### ########## ##### ##### ########## ##### ##### ########## ##### ##### #####So the etching solution would return them to the correct width.A proper etch tank which circulates the solution may eliminate this issue.I just had a container of FeCl that i sat the PCB in and move it around on some wire.

author: DarkPrince
author_rank: Regular Contributor
timestamp: August 23, 2012, 09:57:32 pm
content: Yeah that isn't a problem. I'd mention though, work on a method to... calibrate yourself. Get a feel for how fast the developer works... how fast the acid etches. I had a test pattern where I exposed it for various increments of time, and etched it on the other axis for various amounts of time, to optimize the quality (also had various track widths to test stability of small traces). Good way to know what times to use for different processes.I had taken a break for nearly 8 months since my last etch before two weeks ago... had to get the feel for it back! Timing was off, nearly had bad traces.On the other hand... a turn-around time of only a hour/couple hours is wonderful.
DIY Plug with a switch - Page 1
Forum section: electronics / beginners

author: u666sa
author_rank: Frequent Contributor
timestamp: April 03, 2025, 05:14:44 pm
content: I need this only with a U.S. fork --https://www.vseinstrumenti.ru/product/uglovaya-vilka-dori-s-vyklyuchatelem-s-zazemleniem-chernaya-16696-8920154/#searchQuery=%D0%B2%D0%B8%D0%BB%D0%BA%D0%B0+%D1%81+%D0%B2%D1%8B%D0%BA%D0%BB%D1%8E%D1%87%D0%B0%D1%82%D0%B5%D0%BB%D0%B5%D0%BC&searchType=srpWhere do a find me one? I searched all over.Also, what are these called?https://www.vseinstrumenti.ru/search/?what=%D0%B2%D0%B8%D0%BB%D0%BA%D0%B0%20%D1%81%20%D0%B2%D1%8B%D0%BA%D0%BB%D1%8E%D1%87%D0%B0%D1%82%D0%B5%D0%BB%D0%B5%D0%BCWhere to find a web page with whole bunch of these for the U.S. plug?

author: BILLPOD
author_rank: Frequent Contributor
timestamp: April 04, 2025, 01:26:23 pm
content: Good Morning U666as, I got some of these, not long ago, and they work well. Maybe you could use them:https://www.amazon.com/dp/B07QKPBZX1?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
DIY Power Supply - Page 1
Forum section: electronics / beginners

author: kalimari
author_rank: Newbie
timestamp: October 11, 2014, 01:16:01 pm
content: Hello erveryone,i just saw the video EEVblog#221 and wath thinking maybe i can build one of my own. I read a lot of forums about this topic and found a electrical circuit from de PSU from elektuur 1982. But I was wonder hou I can update it to a synchroon +15V/GND/-15V / 4A and a 0-30V / 4A outputs with LCD for each regulated (potential and current) output. I got a double primary (2x115V = 230V) and double secundary (2x18V/4.44A) transformer (160VA) and a tranformer with single primary (230V) and double secondary (2x12V/ 25VA) transformer.On one forum i read about replacing the LM723 with a Motorale MC1723CL, is this a good idea? I love to build my own PSU but have little problems to vindt parts to hold the amunt of current i wanna have (4A) for de transistors and if anybody can give me a tip hou I can calculate de values of the resistors en capacitors.One final question. Wil the PIC 18F1320 of PIC18f2520 do the job for controlling de LCD. (i got one from a friend)PS sorry for my english but i hope somebody understand my question.
DIY precision voltage follower with Giga ohm input impedance ? - Page 1
Forum section: electronics / beginners

author: BravoV
author_rank: Super Contributor
timestamp: February 28, 2014, 03:03:50 am
content: After watching Dave's EEVblog #584 - What Effect Does Your Multimeter Input Impedance Have ?, just curious how difficult or the challenges if we want to build an add on box for the DMM front end that has Giga ohm impedance ? Just for low DC voltage measurement.Its like uCurrent, a separated box for current measurement to complement the DMM, but this time for low DC voltage and has very high input impedance.Assuming we skip the input protections and other safety measures as in normal DMM does, is it difficult ?As novice, I'm thinking of a battery based circuit with an fet input, low offset and precision op-amp configured as voltage follower, is this enough ?Appreciate some thought from experienced fellows.

author: sync
author_rank: Frequent Contributor
timestamp: February 28, 2014, 05:37:45 pm
content: It's easy. I just breadboarded(!) this circuit. My measurements:Offset voltage (shorted input): <10uVError from -3.5V .. +3.5V: <10uVInput impedance @ -3.5V: >350GohmInput impedance @ 3.0V: >300GohmInput impedance @ +3.5V: >20GohmBias current @ 0V: <30pAFor reliable high impedance I would mount the input path free standing in the air. A problem is that the output is not protected.

author: David Hess
author_rank: Super Contributor
timestamp: February 28, 2014, 07:05:17 pm
content: It is not difficult to do but there are some features besides robust overload performance that I might include:1. Suspend the supply voltage to the circuit to increase the common mode input voltage range by a lot.2. Use a low noise FET with offset correction provided by a chopper stabilized amplifier to lower the broadband and flicker noise.I do not know about currently produced handheld meters but the Fluke 8060A handheld multimeter supports bypassing the 10 megohm input divider to provide > gigohm level input resistance on the 200mV and 2V ranges. My best bench meter, an HP3478A, of course always operates this way on the low ranges which is annoying when a standard 10 megohm input is needed as I discovered once. My Tektronix DM502 3.5 digit multimeter can be jumpered to do this while my higher resolution DM501 4.5 digit multimeter cannot.
DIY-QlockTwo-Project safety - Page 1
Forum section: electronics / beginners

author: PODF
author_rank: Contributor
timestamp: November 28, 2016, 10:23:21 am
content: Hii'm building a project with 110 NeoPixels (3LED's per Pixel). One NeoPixel consumes max. 60mA. So max for all = 6.6A. They run at 5V.Every NeoPixel has +/-/Digital-In/Digital-Out. I never built a project that uses that much Power. Untill today i only built stuff that uses way under 1Amp.So i wanted to ask here for safety-measures i should implement.The powersupply is capable of delivering 10A at 5V.I think i need a 7Amp fuse to protect the thing so if there is a short in the circuit it will not catch fire (the project makes usage of Styrofoam, this burns good).(Maybe i can insert a 5Amp fuse, because the LED's will most likely not run at full power, i have to do tests on this).Is there additional protection i can use? In teardown-videos of dave he is sometimes mentioning a varistor. For input protection. Should i use something like that? Or is this already implemented in the PowerSupply? Should i maybe insert a diode after/before the fuse?I will use a 1.5mm2 cable for powering a short length of prototype-board rails.From there i connect a 1'000uF 16V cap for protecting the NeoPixels from onrush current.From there i will use 0.2mm2 to power 10 separate strips of with each 11 NeoPixels (0.66A max. cable is rated at 1.6A).The prototype-board rails will also power an Arduino. And the Arduino is driving the NeoPixels with one Digital-Output-Pin that has a 300-500Ohm resistor to protect the first NeoPixel.The Datasheet for the 1.5mm2 cable is not mentioning a max. Amps value. But some other Values. Is it possible to Calculate the max. Amps this cable is capable? (Datasheet:http://www.produktinfo.conrad.com/datenblaetter/600000-624999/605926-da-01-en-LIY_LITZE_1_50_QMM_10_M_ROT.pdf)

author: PODF
author_rank: Contributor
timestamp: November 30, 2016, 10:22:42 am
content: On my research on the web i found this pagehttp://www.allaboutcircuits.com/textbook/direct-current/chpt-3/importance-electrical-safety/it gives a very good introduction to electrical safety (human touching electrical stuff)But i'm also concerned about fire. My project must not catch fire. What are the do's and don'ts. What do i need to do that my Project will not hurt anyone? No Fire, No Smoke, etc.I guess that 10A could easy generate enough power to inflame something.Can poor solder-jonints get so hot that they inflame the styrofoam/cardboard? Maybe the Project falls to the ground and then some solder-joints get weaken.Just an idea... are there Fuses that are like through-hole resistors? Then i could use extra 0.7A fuses where i distribute from 6.6A to 11x 0.6A?A thermal camera would come in handy to see if somewhere the circuit gets warm/hot.
DIY RS232 interface cable for Meterman multimeter - Page 1
Forum section: electronics / beginners

author: Recyclojunk64
author_rank: Contributor
timestamp: July 04, 2013, 02:35:11 pm
content: Hi, I'm trying to make a simple serial interface cable for my 38XR's optical data output. I was planning to use a photodiode/transistor and hopefully not having to give it external power.Anyone have any idea on where to start? I've already tested the photo-diode with a transistor and LED to make sure that it worked with the meter, and I'm pretty sure I have to somehow send some sort of signal down to pin2 (Rx) but how do I get the +-3 or more volt signal that I apparently needCheers

author: LBoltzmann
author_rank: Newbie
timestamp: August 30, 2013, 02:16:05 pm
content: I just picked up the 38SW-A serial adapter and software for the Amprobe 38XR-A -- which should be basically the same as your meter. I don't see an easy way to crack open the case, but I can say a little even treating it as a black (red) box.First, it seems to communicate at 9600 baud, 8 bits, 1 stop bit, and no flow control or anything else. The meter talks to the computer but communication in the other direction isn't nescessary -- which makes things a little simpler. I think you only need to connect one of the lines. I haven't deciphered all the codes, but it doesn't look too bad. E.g. if the meter measures 78F, then it sends 0200782A00080.As for how to make it self powered, you can get power from the lines coming from your computer This productdatasheettalks a little bit about how isolation and port power works. You could probably use a switching capacitor inverter to get negative voltages from positive ones (or vice versa).That said, although you could make an adapter to RS232, it's may be easier to do a USB adapter. That way, you'd get power very easily (from the usb) and you wouldn't have to deal with the negative voltages RS232 requires. FTDI is known for making USB to serial chips (I've heard they're fairly easy to use), but I'm sure others make them too.
DIY SMD R/C kit - Page 1
Forum section: electronics / beginners

author: awallin
author_rank: Frequent Contributor
timestamp: December 10, 2014, 08:41:34 pm
content: Inspired byhttp://www.digitalunderpants.com/diy-smd-resistor-capacitor-kit/I made a resistor and cap kit for home-lab.I enhanced the labels a bit with color-coding and included the wattage for resistors and voltage-rating for caps.40pcs small boxes from ShenZhen2U. Paid on Nov 15th and delivered to Finland on Dec 8th - so not exactly fast, but shipping from China is cheaper than from US (e.g. adafruit or sparkfun) - no VAT or customs to be paid this timeset of resistors from digikey:Resistors 1x, 2x, 3.3x, 4.99x over 5 decades from 10 Ohms to 100 kOhms. All 0805 size.Capacitors: 4.7x and 10x over 7 decades from 1pF to 10uF. Smallest 0603, mostly 0805, and largest 1206 size.Bugs: X7R is misspelled as XR7. One printed label was lost in production. My choice of components uses 36 out of 40 boxes - still room for 4 more components.Enjoy!Anders
diy sop16 breakout board - Page 1
Forum section: electronics / beginners

author: m3vuv
author_rank: Super Contributor
timestamp: February 16, 2022, 08:12:24 am
content: Hi all i need a sop16 breakout board/adaptor,would anyone have pcb artwork in pdf format for laser printing,as plan to etch my own rather than wait weeks for delivery,Tia.

author: Zipdox
author_rank: Regular Contributor
timestamp: February 16, 2022, 08:49:05 am
content: That's like 5 minutes in EasyEDA, do it yourself.

author: m3vuv
author_rank: Super Contributor
timestamp: February 16, 2022, 09:49:22 am
content: belive me if i could i would,for some reason any cad software sends my pc nuts.,thats why i am asking ok.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 16, 2022, 10:09:19 am
content: What do you want the TH attachment to be? DIP? How wide?

author: jpanhalt
author_rank: Super Contributor
timestamp: February 16, 2022, 10:34:35 am
content: Here it is: (attachment)Let me know if you want the package outlines removed. I suspect so.

author: m3vuv
author_rank: Super Contributor
timestamp: February 16, 2022, 10:42:37 am
content: its for one of these ok,tia.https://www.aliexpress.com/item/1005001592303429.html?spm=a2g0o.productlist.0.0.6175a877lCryDK&algo_pvid=48fc8e83-c23a-42e4-93e2-cd57a8de5b8c&algo_exp_id=48fc8e83-c23a-42e4-93e2-cd57a8de5b8c-0&pdp_ext_f=%7B%22sku_id%22%3A%2212000018033300106%22%7D&pdp_pi=-1%3B18.18%3B-1%3B-1%40salePrice%3BGBP%3Bsearch-mainSearch

author: m3vuv
author_rank: Super Contributor
timestamp: February 16, 2022, 10:45:47 am
content: its to print using toner transfer so needs outlines removing please,many thanks.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 16, 2022, 10:47:19 am
content: Yes, that central footprint in the pdf I attached. With SOIC and SOP there may be some variation and you didn't specify scale. The attached pdf is on a 0.1" grid. At 1:1, the it will appear much smaller.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 16, 2022, 10:48:42 am
content: What scale? Can you reduce a pdf?

author: jpanhalt
author_rank: Super Contributor
timestamp: February 16, 2022, 10:52:16 am
content: Here is is, everything except pads and traces (top) removed.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 16, 2022, 11:02:57 am
content: Here it is printed 1:1Be sure to confirm actual size that you get.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: February 16, 2022, 06:33:57 pm
content: Go look around oshpark. People put boards on there to share. JLBPCB might do it too. For something like this, ordering it from EBay is a choice too.

author: tooki
author_rank: Super Contributor
timestamp: February 16, 2022, 06:49:31 pm
content: And bear in mind that SO/SOP and SOIC aren’t the same thing, and that different manufacturers use the terminology differently. The only thing they have in common is 1.27mm pitch, but there are (at least) 3 widths in common use.
DIY Stenoboard - Page 1
Forum section: electronics / beginners

author: ziegler
author_rank: Regular Contributor
timestamp: January 03, 2016, 12:10:25 am
content: I’m been wanting a Stenoboard for some time now, but I couldn't buy it, because it will cost way more than the price listed, when I get it here in Denmark.(Anything shipped to here, from outside Europe, will add a lot of extra cost, when it goes though the airport)https://github.com/caru/Stenoboardhttps://github.com/caru/StenoPCBhttps://github.com/caru/Stenoboard/wiki/Assembly-Manual---DIY-kitSo I thinking about making it my self.The parts will be bought from ebay-china, eu.mouser or farnell.comI will get a 3D printer in about 3 months’ time (Love that cheap price, on an early Kickstarter project), so the Stenoboard-case is covered there.But I looked at the price, it would take to get the PCB-boards printed, and that gonna hit my budget really hard.I am new to this world of hobby electronics (even this project will be a milestone to reach), so I don't know Which website got the best price for doing single boards.(Keep in mind that it need to be in Europa)Or maybe I can use a Stripboard to redesign it (the Kicad project file is kind of hard to read, but it looks like it got a different design on each side).Any tips or help, will be greatly appreciated.

author: ziegler
author_rank: Regular Contributor
timestamp: January 03, 2016, 02:29:22 pm
content: I didn't see that the web-shop where you buy all the stuff from, ship all the produces from Italy.(I feel so stupid)So this page is closed for now. Probably gonna update this page when I'm done with it (or get stuck somewhere).
DIY Strobe light - Page 1
Forum section: electronics / beginners

author: S1Co
author_rank: Newbie
timestamp: November 20, 2015, 06:41:51 pm
content: Hey guys, so recently I decided I want to build my own Strobe light and after I've made my quick prototype along with my Arduino Mega and a Breadboard, I decided it's time go to PCB board and to go bigger as well. See the problem is that while I had my 15 LED's on my Breaboard it was simple enough wiring them up, I just used my 1-221 (220 ohm) resistor chips to wire them up individually, and the results were good enough. Now though my PCB will have 44 of those LED's, plus another 22 (A 11 line of Green and a 11 line of Blue) LED's, just to act as an additional effect. So, I want to be able to control my 44 White LED's and to be able to control the 11 Green and Blue LED's separately using my Arduino this time. Now the thing that worries me is that I don't have 66 resistors and also that my USB Arduino wouldn't be able to produce enough current for all of the LED's. I'm thinking I could probably use a Transistor along with a 9V Battery or a 12V Adapter or anything like that, but, do I still have to buy 66 Resistors to go along all of the LED's? Or is there perhaps a more clever way to at least get rid of some of the resistors (Ideally all of them)? And also what would have to be my wiring configuration? If anyone ever done any projects like that, would you please provide me with some sort of reference or anything like that? Thank you so much guys.

author: S1Co
author_rank: Newbie
timestamp: November 20, 2015, 06:49:40 pm
content: Some additional information of the LED's.

author: rgawron
author_rank: Contributor
timestamp: November 20, 2015, 08:15:07 pm
content: There are better ways (look for LED current driver), but below circuit will do the job I think, each such transistor per each color of LEDs. The transistor type on my picture was chosen randomly, don't suggest on that.

author: S1Co
author_rank: Newbie
timestamp: November 20, 2015, 08:47:26 pm
content: Thank you so much I'll start getting into that right now and see what I can figure out!

author: S1Co
author_rank: Newbie
timestamp: November 20, 2015, 09:22:13 pm
content: Sadly, while it works for the smaller branches, the white branch is what I'm still having problems with.

author: rgawron
author_rank: Contributor
timestamp: November 20, 2015, 09:29:53 pm
content: White LEDs require higher voltage, try to use two LEDs in series instead of three.