hybridfree/eevblog-posts huggingface dataset:
Making a simple electronic foot pedal for DC Motor control - Page 1
Forum section: electronics / projects

author: davidmadd
author_rank: Newbie
timestamp: October 25, 2017, 09:49:27 am
content: Hi All - I am seeking help or inspiration to make an effective pedal for controlling a DC Motor. The project ultimately is to use DC motors to power an Industrial Sewing machine. I am using 24v permanent magnet DC motors from a variety of sources. I am using a switching 24v DC supply at 20A. The motor controller is either inexpensive 24V Speed controllers from China or more expensive Electromen em 241 DC Controller ( I have both available) but the problem comes when I need to find a foot pedal that controls a potentiometer to give that finite control. I have made one foot pedal that works but it is fiddly, made from plastic rack and spur gears and not particularly robust, but it does work and prove the project is a goer. I would like to make a simpler electronic pedal which would minimise moving parts. I have asked some manufacturers about suitable products and have been told that it would be feasible by using Hall effect/Rotational Sensors/Infra Red sensors/ accelerometers and no doubt more....what I need is some advice on just how I might achieve any of these. I like the sound of Hall Sensor and can understand the principle. Absolute accuracy is not an issue as the speed will eventually be controlled by my foot and I can press harder or softer to achieve the speed I want. Slow speed control is what I am after with the ability to go faster on ocassions. I am not an electronics engineer and need advice in simplistic terms but do have a usefuk workshop and can manage the engineering side of things.Can anybody offer advice on a suitable system with advice on how the outputs from the device would interact with my motor controllers. The cheap chinese ones work ok with a potentiometer but am unsure if other outputs from different devices would actually work. The more expensive Electromen controllers will work with pulse inputs and potentiometers and I assume the pulse inputs would come from Hall effect sensors but dont know what outputs the other devices give.Thanks tpo all in for reading this and special thanks to anyone who might be able to offer advice on a way ahead....

author: Psi
author_rank: Super Contributor
timestamp: October 25, 2017, 09:53:35 am
content: you could look at TIG welding foot pedals from china.They use pots to, but could serve as a nice metal case with pedal for you to implement a hall sensor solution.https://www.aliexpress.com/item/2016-High-Quality-Free-shipping-new-LMM-welder-machine-welding-foot-pedal-control-current-for-tig/32684804717.html

author: Mjolinor
author_rank: Frequent Contributor
timestamp: October 25, 2017, 10:08:31 am
content: Not having specifics of the installation I would advise optical rather than magnetic. Any switched power of significant watts will make EM fields that can affect Hall effect sensors. Better to go with a simple LED transmitter and a photo transistor (analogue).
Making a uhart signal wireless - Page 1
Forum section: electronics / projects

author: Sparky_Freak
author_rank: Contributor
timestamp: March 04, 2022, 04:40:34 pm
content: Hi,I need some advice can you connect a uhart signal to a ESp32 and access the data over Bluetooth or WIFII am currently working on a project and i need to be able to access a device wirelessly currently I can connect to it over usb. however i noticed a uhart output when I took it apart and was wondering if I can access it wirelessly so I can control the device wirelessly.Thanks.

author: rstofer
author_rank: Super Contributor
timestamp: March 04, 2022, 05:24:11 pm
content: One way would be to make the ESP32 into a Telnet server to which you can make a TCP/IP connection via WiFi for example. The other side of the server would be the UART.https://www.arduino.cc/reference/en/libraries/esp-telnet/https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/uart.htmlETA:You wouldn't actually need the full Telnet protocol, you could just as easily do a Berkeley Socket.https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/lwip.html

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: March 05, 2022, 03:42:02 am
content: I have a project that has a PIC18 and a PIC24 communicating with each other through their respective UART peripherals attached to a pair of married Bluetooth modules. It works perfectly.
Making a USB 2.0 cable - what are the requirements? - Page 1
Forum section: electronics / projects

author: Artlav
author_rank: Frequent Contributor
timestamp: September 24, 2017, 08:17:51 pm
content: So i'm making a little rover-like thingy with a couple of cameras on a pitch-yaw rig.The cameras are regular USB webcams, and the cables from them are quite stiff, enough to push them out of place in many positions.I wanted to make a shorter and more flexible cable, USB 2.0 and about 10-20cm in length, going through the least-moving parts of the rig.There does not seem to be any ready-made thin or flexible USB cables that aren't marked as "USB 1 only" or "charging only", so it looks like i'll have to make my own.The question is - what is important in a USB cable?I've tried connecting USB over loose wires before, and more than a couple cm of that is enough to make it stop working.Does it have to have shielding?Does it have to have the differential pair twisted in a certain way?Are there any other requirements?

author: alm
author_rank: Super Contributor
timestamp: September 24, 2017, 10:02:13 pm
content: Download theUSB 2.0 standard. In the version I have locally, sections 6.3-6.7 are about the mechanical and electrical requirements for the cable, including references to other sections of the document. For full or high speed (which you are likely using), the standards requires a twisted cable with a specific capacitance and impedance with shielding around the data pair (D+/D-). That might also explain why all the thin, flexible cables are only rated for low speed, which does not require twisting or shielding.

author: Pack34
author_rank: Frequent Contributor
timestamp: September 25, 2017, 09:47:34 pm
content: What about right-angled cables?I tend to use these guys for specialty USB cables.http://www.usbfirewire.com/ucables.html

author: texaspyro
author_rank: Super Contributor
timestamp: September 25, 2017, 10:06:13 pm
content: I have successfully used plain ribbon cable for short run local USB links. Run ground lines next to the data lines as shield wires... if you have data issues, try connecting the shield wires to ground at only one end. Double up the power/ground wires.I think my standard was something like shield, DATA+, shield, DATA- GROUND GROUND PWR PWR

author: stevelup
author_rank: Regular Contributor
timestamp: September 27, 2017, 07:32:28 am
content: Apple USB cables are very thin and flexible, but you can be sure they perfectly meet the specification. Perhaps cut one of those up?
Making a voltage controlled bidirectional resistor - Page 1
Forum section: electronics / projects

author: dmendesf
author_rank: Frequent Contributor
timestamp: July 23, 2022, 07:36:14 pm
content: I need to make several (16) voltage controlled bidirectional resistor. My plan is to use a PCA9685 followed by second order low-pass filters (RL-RL) driving leds in optocouplers. For the optocouplers the obvious options would be vactrols or h11f1, but both are big and expensive. Has anyone tried to drive photoMOS optocouplers like AQS225R2S in the linear range? Any other ideas? I considered digital pots but they're expensive and don't work at high frequencies (hundreds of khz).

author: David Hess
author_rank: Super Contributor
timestamp: July 24, 2022, 12:53:18 am
content: Multipliers and operational transconductance amplifiers can synthesize a voltage controlled resistor. Another method uses operational amplifiers and a pair of JFETs or MOSFETs as shown below, with one FET in the feedback loop to set the gate voltage of the other.
Making an arbitrary waveform generator more useful - Page 1
Forum section: electronics / projects

author: filtatosv6
author_rank: Newbie
timestamp: March 03, 2016, 12:28:46 pm
content: I am trying to make my wave generator more useful for future projects. I am NOT an electronics guy, I am an electrician that can understand some electronic basics.So what I found out very quickly is that the generator is not a wavy power supply in any shape or form. I can't draw enough amps out of it before I short it out.My question is can I find or make something like an inverter that will supply and control Vpp from a power supply and control the waveform output from my wave generator. If the answer is very common or obvious please be nice to me and point me to the right direction. Thank you.

author: Buriedcode
author_rank: Super Contributor
timestamp: March 03, 2016, 12:42:47 pm
content: So, it seems what you are after is a power amplifier - something that takes in a waveform, and outputs that waveform with a lower output impedance, and variable amplitude (peak-peak voltage).Most function generators have a 50 ohm output impedance, with short circuit protection so nothing gets damaged when the output is shorted, or is driving a low resistance.You could use an opamp driving bipolar transistors but this has frequency limitations, so, for higher frequencies, one could use an IC specific for that purpose, a high current unity gain buffer. In order to control the 'Vpp' from the amplifier, you would either have to vary the gain, or use a fixed gain and have a voltage divider on the input.What are the specs of your arbitrary waveform, and what kind of currents would you need?

author: sca
author_rank: Regular Contributor
timestamp: March 03, 2016, 12:45:55 pm
content: http://www.kepcopower.com/bop.htmBig, heavy, built like tank, crop up on ebay very occasionally.sca

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 03, 2016, 02:29:21 pm
content: Push–pull_output

author: filtatosv6
author_rank: Newbie
timestamp: March 04, 2016, 08:22:05 am
content: Quote from: sca on March 03, 2016, 12:45:55 pmThis is a commercial solution to what i wont and you are right. It is big, heavy, expensive and out of my league. I will keep an eye on them if i find one in my country. ThenxQuote from: Buriedcode on March 03, 2016, 12:42:47 pmI have a basic gen Rigol dg1022. Probably i wont exceed 2-3 AmpQuote from: Mechatrommer on March 03, 2016, 02:29:21 pmThis is more to what i had in mind. A simple solution. I have more reading to do.Some of my thoughts was to hack my wave in an audio amplifier until I burn the crap out of it. Or to hack a UPS to make do what i wont.Soon I will let the smoke out from something for sure.
Making cheap 900mA CC PSU adjustable. - Page 1
Forum section: electronics / projects

author: 3dgeo
author_rank: Frequent Contributor
timestamp: June 15, 2021, 02:23:54 pm
content: Hello,I bought thischeap CC PSUsto power 10W 900mA LEDs.I would like to make LEDs dimmable, I know I can add external PWM dimmer and be done, but it's also a learning oportunity.Even tho I have nothing against natural selection I thought I would ask input before I became a victim of itI know the risk and dangers of messing with it and high voltage so no need for fear mongering.MCU marking: IAD21CX (I think)I did some tracing (skipped low side and AC side) and this is what I found:From what I understand they used simple resistors (2x 390K on a low side and 10K on high side) to power the MCU (I'm assuming it's VGND and VIN of the MCU).Current shunt is parallel array of 1x 2R00 and 3xR820 (0.24 Ohms total). Shunt height side goes thru 56 Ohm resistor to MCU, shunt low side jumps via 0 Ohm resistor and goes to another IO, tho this signal is pulled down via 10K resistor to VGND.I'm guessing diode on the top left and 200K 5 resistor array is for transformer freewheeling and MCU sensing of it? That part of the circuit is most mysterious to me...I assume to make it adjustable I need to increase shunt voltage difference (decrease lower shunt signal voltage) to trick MCU that load uses more current than it actually is.I will stop here and see what smarter people has to say about this circuit.Cheers.

author: Terry Bites
author_rank: Super Contributor
timestamp: June 15, 2021, 05:03:29 pm
content: This is a mains powered item so stop right there!I seriously doubt it has an mcu. Just some shabby LED driver IC.This thing will probably kill you on a good day.Do not mod it!
Making electrical connections to a carbon fiber tube? - Page 1
Forum section: electronics / projects

author: e100
author_rank: Frequent Contributor
timestamp: July 19, 2018, 05:25:49 pm
content: I have some 22mm and 10mm carbon fiber tube left over from another project and because of its corrosion resistance I was wondering about using it to make a capacitive liquid level sensor for use in salt water. I'll insulate the inner tube and leave the outer tube in electrical contact with the water. The salt makes the water behave like a dead short so the dielectric will be the insulation layer covering the inner tube.I searched on Google but couldn't find any fittings designed for making electrical connections to carbon fiber. It's brittle so conventional fasteners aren't going to work. The current is only going to be milliamps, but the connection resistance needs to be consistent over time.I had a look at silver loaded epoxy but that is super expensive at $150 for 15g and I'll probably only use 10% with the rest going to waste.Would brass wire wool or EMI conductive rubber under a hose clamp work?Would double sided conductive copper tape give a consistent connection over time?

author: David Hess
author_rank: Super Contributor
timestamp: July 19, 2018, 06:41:25 pm
content: I have had good results with a mechanical connection using a machine screw and star solder lug but I am not sure how to apply that to such a small diameter tube.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 19, 2018, 07:16:17 pm
content: Sand the surface to expose fibers, then wrap with a hose clamp?Tim

author: duak
author_rank: Super Contributor
timestamp: July 20, 2018, 07:19:26 pm
content: I'm not sure where you are but perhaps a trip to a local plumbing store to look for Compression Fittings. These are fittings for tubing where a metal or plastic sleeve or ferrule slips over the tubing and is then locked in place by a nut with a tapered center hole. These compress the tubing radially and I think if not overdone will not damage the tubing. Here in Canada, they are available in brass, chromed brass and stainless steel. Since you are working with salt water, there might be some electrochemical effects from the metals of the fittings. I believe stainless or chrome will be the most salt water resistant, or will at least balance out any effect if the same metal is used at both ends. It might make sense to find a polymer fitting and find a metal sleeve or ferrule that you can connect an insulated wire to to keep the connection away from the salt water.Cheers,
Making my own buffer circuit - Page 1
Forum section: electronics / projects

author: drakejest
author_rank: Regular Contributor
timestamp: September 29, 2021, 02:26:45 am
content: So i am in need of a 50mA single channel buffer circuit, since i could not find one i was thinking of making my own push-pull using this N - P channel mosfetSIA517. My input logic is 3v3 volts and will be pushing/pulling 5v.Can i do it this way>? am i missing something important that are present in those timeless classics such as 74LVC/74AHCT ?

author: magic
author_rank: Super Contributor
timestamp: September 29, 2021, 05:57:33 am
content: Two problems with a discrete solution:- potential crossconduction when the input is at 50%- the P-ch will always see at least -1.7V at its gateThis may work if the FETs have high enough threshold voltage (like >2.5V) and still enough conductance at Vgs=3.3V to drive 50mA.Possible alternative: something like 74HCT2G04, parallel both sections.

author: drakejest
author_rank: Regular Contributor
timestamp: September 29, 2021, 06:47:39 am
content: Quote from: evb149 on September 29, 2021, 04:06:26 amI have a 1nF line capacitance that i need to overcome, thats why i need such a high current buffer. Paralleling buffers feels not right.

author: drakejest
author_rank: Regular Contributor
timestamp: September 29, 2021, 08:11:11 am
content: Quote from: magic on September 29, 2021, 05:57:33 amQuote from: evb149 on September 29, 2021, 04:06:26 amThe TI guide although were helpful, but i did not quite get the perfect chip. They all need me to shift the voltage up before i can use them. Till i found this chip74ABT244. No need to to shift the voltage up as its 5v vcc it only needs 2v Vhight. Its also 8 CHANNELS. I will parallel 4 of those each capable of 32mA. This is the chosen one ! haha.What do you think?
Making my own project box?  - Page 1
Forum section: electronics / projects

author: Hextejas
author_rank: Frequent Contributor
timestamp: July 01, 2018, 03:52:48 pm
content: I have a small cardboard box that is the perfect size for my project. I need something to be able to paint on, that will stiffen it so that I can drill it, etc.Have you ever done anything like that ?Thanks

author: anishkgt
author_rank: Frequent Contributor
timestamp: July 01, 2018, 03:54:34 pm
content: Plaster of Paris, dry it, sand it and paint.Www.Georgehobby.wordpress.comEquipments: DSO104z, Hakko FX888D, Brymen BM869s

author: CopperCone
author_rank: Super Contributor
timestamp: July 01, 2018, 03:55:04 pm
content: Well if you don't mind how trashy that is, you can soak it in epoxy. I use the epoxy from the jewelry store, the two part clear resin, to soak into cardboard tubes (like paper towel rolls) to make them stiff. It's OK for winding signal inductors you don't care too much about. You just brush it on and let it drip off. I sit them on a wire shelf.Thin super glue will work to stiffen something too but its kind of expensive.

author: CopperCone
author_rank: Super Contributor
timestamp: July 01, 2018, 04:11:59 pm
content: dont spill anything on elmers glue, or if you use it, at least give it a topcoat with something water proof

author: Joebeazelman
author_rank: Regular Contributor
timestamp: July 01, 2018, 09:50:07 pm
content: If you want stiffen it, use plain old wood glue or white elmers glue as a paint. If you really want to stiffen it more, You can layer on paper and or cardboard on the inside or outside. I would then paint it in your favorite color. Try not to sit on it, swim with it, or smoke stuff in it.
Making nixie tubes - Page 1
Forum section: electronics / projects

author: texaspyro
author_rank: Super Contributor
timestamp: October 15, 2018, 01:52:47 am
content: A forum search did not find this interesting video, so here goes:https://www.youtube.com/watch?v=wxL4ElboiuA&frags=pl%2Cwn

author: bloguetronica
author_rank: Frequent Contributor
timestamp: October 15, 2018, 02:47:44 am
content: Always nice to see! Thanks for sharing!Kind regards, Samuel Lourenço

author: Gyro
author_rank: Super Contributor
timestamp: October 15, 2018, 03:53:41 pm
content: The forum search always did suck though.https://www.eevblog.com/forum/reviews/making-of-nixie-tubes/msg1422150/#msg1422150Always worth a reminder to watch it again though!
Making of a Micro SD Card Breakout Board - Page 1
Forum section: electronics / projects

author: NorDevX
author_rank: Newbie
timestamp: September 22, 2015, 08:34:10 pm
content: Just made a video on making a Micro SD card breakout board. Let me know what you think! Don't be too harsh it's my first video : )

author: stevenhoneyman
author_rank: Regular Contributor
timestamp: September 27, 2015, 12:36:25 pm
content: Just my honest-but-not-too-harsh opinion...It doesn't show or explain an awful lot, and because the socket hides the solder from view, it looks the same when it came out of the oven as when it went in!I also did wonder why you went to all this trouble (stencils, connectors, lead free paste (yuck!), boards, and your time) when versions that also include pullups/buffers/regulators/etc can be bought for under £1/$1 in single quantities.e.g.http://www.ebay.co.uk/itm/TF-Micro-SD-Card-ModuleMini-SD-Card-Module-Memory-Module-Arduino-ARM-AVR-/141785241466http://www.ebay.co.uk/itm/Micro-SD-Storage-Board-Mciro-SD-TF-Card-Memory-Shield-Module-SPI-For-Arduino-BH-/311434555926http://www.ebay.co.uk/itm/TF-SD-Card-SD-Ramps-Breakout-Module-For-Teensylu-Sanguinololu-3D-Printer-Reprap-/141672686647Again just my thoughts, feel free to ignore. I assumed this wasn't a "learning to solder SMD" type excercise, with you already owning a non-DIY reflow oven.
Making of a quartz main clock for slave clocks - Page 1
Forum section: electronics / projects

author: compet17
author_rank: Regular Contributor
timestamp: May 21, 2019, 08:25:22 am
content: Since a couple of years I have a Solari Dator slave clock that needed a new master clock to drive it. So I made one... with all old school 74-TTL and 40-CMOS chips and all the stuff I had in my drawers. Then designed a board, sent the data to PCBway in China and got some beautiful PCB's back about one week later.Here is the video about it:I also explain the schematic diagram...
Making old phone ring (central phone) - Page 1
Forum section: electronics / projects

author: Asd20752
author_rank: Newbie
timestamp: June 03, 2015, 09:00:50 pm
content: I have this old phone from back when it was centrals who set you over to the person you requested. All I want is it to ring on the flick of a switch. Do not have any testing equipment to work with. On the inside I found the plan/sketch. I personally do not know electronics and can not read sketches. So hoping someone can help me out with an easy solution.Too large image, could not upload as attachment. Sohttps://drive.google.com/open?id=0B9C3_NWm3y7hUGctcFNORWNZUHc&authuser=0Sorry for poor picture quality, not easily placed stickerThank you-Adrian B. Hoffsten

author: albert22
author_rank: Regular Contributor
timestamp: June 03, 2015, 10:51:17 pm
content: You need a ring generator. A simple transformer can do it because an AC signal is required. If you want the cadence of the ringing then it gets a little more complicated.More info about ring generators and voltages here:http://www.epanorama.net/circuits/telephone_ringer.htmlHand operated:

author: German_EE
author_rank: Super Contributor
timestamp: June 04, 2015, 08:17:03 am
content: You need to feed about 90V AC into the phone to make it ring.
Making solid state relay with BT139 a bit confused with - Page 1
Forum section: electronics / projects

author: Chriss
author_rank: Frequent Contributor
timestamp: September 18, 2022, 10:47:46 pm
content: Hi!I have several BT139 and MOC 3021 around and I come across my mind I could make solid state relays for AC loads like AC motors and lamps.I know, restive and inductive loads are different, I would like to make all them to handle inductive loads, so I need also the snuber circuit if I'm not wrong.My major problem is to setup the right value on the circuit.I checked around the net and found tons of schematic promising to do what is written, but I'm not really trusty to them.Can somebody pls share a working schematic how to make my relays?Here is a schematic which looks ok for me, I would substitute the BT136 with BT139, probably not a problem.https://www.twovolt.com/2016/11/29/solid-state-relay-using-moc3021-bt136-traic-circuit-pcb-layout/What is this meaning in the datasheet of the triac:Igt trigger current VD = 12 V; IT = 0.1 A; T2+ G+ ?What is T2+ G+ standing for?Any help I would really appreciate.Thank you.

author: nigelwright7557
author_rank: Frequent Contributor
timestamp: September 18, 2022, 10:52:59 pm
content: Quote from: Chriss on September 18, 2022, 10:47:46 pmMT1, MT2 and G are the pins of a triac.Turn on triac by applying volts across G to MT2.

author: Chriss
author_rank: Frequent Contributor
timestamp: September 18, 2022, 11:03:55 pm
content: Thanks for fast response.If I understand you correctly, In the schematic I put on the link, the turn on voltage is achieved through the T1 and G ?Would this schematic work in practice?I'm new to triac's and not really practiced with them, but I'm familiar with AC voltage and safety of mains...I found this nice doc, maybe somebody who is new to triac can also learn from it, like me.https://www.st.com/resource/en/application_note/dm00451014-controlling-a-triac-with-a-phototriac-stmicroelectronics.pdfThanks.

author: Terry Bites
author_rank: Super Contributor
timestamp: September 20, 2022, 09:23:46 am
content: I'd read this app note from ST AN437 on snubbers for inductive loads. Choose your C and with care. CY caps and R that can safely dissipate the transient energy.Triacs are satan's spawn. I hate 'em.DIY dimmer trauma in childhood.

author: nigelwright7557
author_rank: Frequent Contributor
timestamp: September 25, 2022, 10:52:13 pm
content: Quote from: Chriss on September 18, 2022, 11:03:55 pmThe circuit is part of a working circuit.You need 5 volts between "TRIAC" signal and ground to turn it on.
Making some General purpose wireless sensors/controlers - Page 1
Forum section: electronics / projects

author: TommyGunn
author_rank: Contributor
timestamp: April 22, 2014, 03:02:55 am
content: Hey everyone,Out of boredom I’m making some wireless devices for use as door sensors, light sensors and some other sensors to and outputs to just control things around my house. I’m working on the hardware alone so perhaps you guys can scrutinize my work.Here is the schematic. Hoping to run a batch of these boards in a week or 2. Thoughts? Maybe I can add some stuff to make it better?
making spiderman web shooters retractable - Page 1
Forum section: electronics / projects

author: Darkmaster
author_rank: Newbie
timestamp: November 26, 2021, 09:59:31 am
content: I've been struggling to brainstorm how to get my mechanical webshooters to retract its web line (thread) after being shot at full distance. But I need something very compact and enough to fit into the area where the reel is located and screwed in. So far I tried using retractable badge holders, the smallest retractable tape measurers (Yes I had to dissasemble them to experiment with the recoiling spring), to looking up motors that might produce retracting motions but to no avail. Is there any way I can make the web line (thread) retract back to the nozzle or any component(s) that is the most compact and basic in terms of expected functionality? Sean's Crafts on Youtube produced a similar one but his design and production was from scratch but I already had a fully asssembled pair of webshooters. Any suggestions or advice on how to achieve this with an already completed version.... or shall I say, modify it to retract the way I want it to?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 26, 2021, 04:26:32 pm
content: I'm thinking of a RC sailboat winch servo. But those things are a bit big and I don't think they have a one-way clutch either.

author: Darkmaster
author_rank: Newbie
timestamp: November 27, 2021, 01:20:18 am
content: What a pity. If only they were compact and easier to integrate.
Making step function in Opa transfer function - Page 1
Forum section: electronics / projects

author: dobsonr741
author_rank: Frequent Contributor
timestamp: June 25, 2023, 07:12:44 pm
content: I’m looking to have a schematic to create the following DC transfer function:Is should the precise in the linear 1 V/V region. Any ideas to share?

author: magic
author_rank: Super Contributor
timestamp: June 25, 2023, 07:23:27 pm
content: Get some LM358 or whatever dual opamp that works down to ground.Wire one channel for unity gain with nonzero feedback resistor.Configure the other as comparator. At low input voltages, the output goes up and pulls the unity buffer's IN- by means of a diode, overriding normal feedback and forcing its output to ground. At high input voltages, it goes down and the diode prevents it from disturbing the buffer.Input impedance of the whole circuit is just two opamp input pins. High and constant over the whole range. But watch out for opamps with differential clamping diodes.

author: Terry Bites
author_rank: Super Contributor
timestamp: June 28, 2023, 09:44:34 am
content: Keep it simple and DC accurate. An opamp free zone.Compare Vin with your "dead zone" threshold using a comparator. Use that to control an analog switch. Switch between Vin and ground (or what ever level you like).You can use what ever switches and comparators you prefer, single or dual supply- what ever suits. You may need a little hysteresis to reject false switching events.If you want it to be bipolar use a window comparator.Or be decadent and use an opamp with shutdown instead of the analog switch. eg OPA211 and many more shutdown types will work.You do need a pulldown or other path to 0V, the outputs of these opamps go High Z when disabled.
Making the voice recording time of a megaphone longer - Page 1
Forum section: electronics / projects

author: Manuroe
author_rank: Newbie
timestamp: June 15, 2023, 10:36:16 pm
content: Hello eevblog forum members.I came here to this forum in the hope that I would find somebody who has any knowledge about the project I am working on. Firstly because I can not find the right IC identifications and secondly, I am doing this project for somebody else and just don’t have the time to completely start reverse engineering this device.The problem is the following, an acquaintance of mine has a megaphone “VONYX 952.016” that can record your voice for about 10-15seconds, next to this it also has aux input, Bluetooth, siren function, etc. This person would need it to record for about 60-120seconds.I asked this person to verify first that it wasn’t possible to buy another model that had these capabilities of course, but apparently for some reasons what she needs in a megaphone (wattage, size, features) it is not readily available. So customisation it is!I was thinking at first that the voice would just be recorded in an IC that would be easy to trace, and then maybe replace with a model that has a longer recording time. Sadly I can not trace some components. And for the moment I don’t have time to scope everything out.I have attached some pictures here to give you an idea what is inside. But I am obviously not able to give a schematic. In the main body there are 2 pcb’s. Mostly for Bluetooth and amplification. In the detachable microphone there is 1 pcb. And I am thinking that the sound recording happens there. (But I might be wrong).Again I am not expecting anybody to reverse engineer this, I know that’s impossible almost with just some pictures but If anybody has any experience with a repair of design of these devices, maybe all these Chinese megaphones are the same? any information is welcome.I will add needed details or forgotten information tomorrow if anybody is interested. And some better pictures!Thanks for the read!

author: minifloat
author_rank: Contributor
timestamp: June 15, 2023, 10:45:48 pm
content: I have a possible solution to this, but do not know whether the solution is feasible.The megaphone has bluetooth and AUX input. So, connect a smartphone, running a voice recording app, wired or wireless, to the megaphone.Also, an old smartphone would do the job, if operation independent from daily used smartphone is needed.What do you think?br, mf
Making the X-Tronix 9000 vacuum tool work - Page 1
Forum section: electronics / projects

author: kingofkya
author_rank: Regular Contributor
timestamp: October 13, 2014, 04:43:16 am
content: This is one of the most disappointing tools i have used, someone obviously did the right stuff inside, then some one saved a penny or got rushed out the door.So my quick over view.What works out of the box.Hot air gun.Its very quiet, who ever designed the mechnaical isolation did a great job.What dosen'tSolding iron cable is way too bulky to be used.Use less suction attachment on the iron is constantly in the way.Vacuum pickup tool relies on leaking air to work small hole on pen.Too much vacuum for hole to work on lowest setting.Tip is way too big for any smd work(found smaller ones on ebay)So this idea has been in the back of my head for the past year or so since i got this thing. (and watching mikeselectric stuff videos on the subject) Anyways I wanted to some how add a valve to the suction side so I can electronically switch it on and off. So i found theses small solenoid valves on amazon.http://www.amazon.com/gp/product/B00GGRNAUI/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1So the first thing is did was put one directly in line... well that didn't work it the smd part stayed firmly stuck to the tool. Ok so i also needed a release valve, because the vacuum stored in the tube needs to drop for the part to released.So that worked great.But now I needed to invert one pump so one is always on the other is off. A simple realy with NC and NO terminals fit the bill nicely. So i added a cap rectifier, and the relay and wired it all up. And i found a nice 10v tap that work wonderfully for my purposes.(green wires)In the pic you can see my release valve and relay nicely zip tied down. As well as some factory workers questionable use of the red hot glue gun.And here is the result:) I am quite happy because i have some board to build up with a few hundred smd leds this will make it quite easy. I just need to build a foot pedal.And this sums up the workmanship of this thing.
Makita battery - USB-C charging - Page 1
Forum section: electronics / projects

author: kat
author_rank: Newbie
timestamp: March 29, 2024, 07:35:44 pm
content: I found this knock-off Makita battery charger that is able to take power from a USB-C PD charger.So basically you could charge Makita batteries through USB-C. Charger is also much more compact that the original Makita bulky AC charger.And this charger does both input and output!...but.. how safe is this for the batteries?Because I see on the back that it only has 2 rails, for -/+. It has no connections to the middle yellow housing with 7 pins like the original AC charger does.So I assume it does no balancing?Is this bad for the battery?

author: BILLPOD
author_rank: Frequent Contributor
timestamp: March 30, 2024, 01:43:12 pm
content: Good Morning Kat, get one of the USB testers and insert it into your circuit and see what it is doing. You need a tester that recognizes the quick charge modes, like the phones use. The tester I like is the J7-c,which is found everywhere.
Malfunctioning circuitboard - Page 1
Forum section: electronics / projects

author: TechyGuy17
author_rank: Newbie
timestamp: December 15, 2024, 10:51:30 am
content: Hello guys, student here working on a project, its a small linux board with a allwinner H616 and bare minimum required parts to make it work and communicate with it. The boards were manifactured by JLCPCB and parts gotten from LCSC to solder.My problem:I do not get any voltage out on the CPU rail of the PMIC, its a axp313a2) The CP2102 chip does not get recognized by windows, gives an error about malfunction during the "interview".3) Even with a quick solderjob were I steal power from the GPU rail to the CPU rail it seems to be rather "dead", I used a arduino uno as temporary serial converter but its completely blankThis is the github project I made for it:https://github.com/TechyGuy17/kryptokrona-mini-minerTo get the PMIC working with the CPU it required some patches of the linux kernel, so please check those for the voltages.As I live in Gothenburg I asked for help at the Chalmers electro sections lab, a very nice guy helped me for 4h but with no success. If you have time please look through the project and tell me if you find anything thats wrong.

author: Krotow
author_rank: Regular Contributor
timestamp: December 15, 2024, 09:48:37 pm
content: Quote from: TechyGuy17 on December 15, 2024, 10:51:30 amA lot of counterfeit CP2102 chips in circulation was a reason why Silicon Labs pulled the plug and denied to use their Windows Drivers for CP2102 chip at all. They have a new chip CP2102N which works with their drivers.
Manhattan-style ion optics/Mass spectrometer? - Page 1
Forum section: electronics / projects

author: ChristofferB
author_rank: Frequent Contributor
timestamp: January 04, 2022, 09:59:08 pm
content: This came to me in a brief flash of briliant, distilled, lathelessness and milllessnessBackground: I want to build experiment with ion optics, electron guns, mass spectrometers in high vacuum.Problem: I don't have the machining tools (lathe, mill) one would like to fabricate electrodes, and other elements, and mount them mechanicallyIdea: "manhattan style" construction in vacuum - using Rogers substrate PCB (PTFE/Ceramic microwave PCB), soft soldering electrodes and ion optics components to it for a near-perfect 2D layout.Substrate is VERY insulating, capable of handling high voltage.Having a ground plane close by might be an issue, but then in a steel vacuum vessel, everything is encased in ground plane.-Little vertical pcbs with holes cut could be made to hold electrode elements. Insulators and PCB layout would mostly be simple enough to just draw with a brush dripped in etchant.This is a very off the cuff idea, but I'd like some input. Could work, or waste of expensive PCB material?
Manufacturing custom connector for Screen printed electrodes - Page 1
Forum section: electronics / projects

author: glompos21
author_rank: Newbie
timestamp: January 11, 2014, 03:23:41 pm
content: Hi to all,I am a postgraduate- student in Technical University of Crete. As part of my dissertation I want to use screen printed electrodes (http://www.dropsens.com/en/screen_printed_electrodes_pag.htmlModel: DRP-8X550). I have searched the internet and did not find any connector within my budget limit. So I plan to make my own. I have almost completed the design the 3D model of the connector (in Creo 2.0).I plan to use a 3D printer to create the model. However the problem that I am facing is that I do not know from where I can buy the pins, in order to complete my design. The dimension of surface pins on the screen printed electrode is 1mm X 8mm.Thanks in advance

author: kony
author_rank: Regular Contributor
timestamp: January 11, 2014, 08:43:31 pm
content: I didn't find any dimensional drawing, but look for flatflex cable connectors.Something like theese :(Connector on image above is connfly DS1020 series, 2,54mm raster.)

author: larry42
author_rank: Regular Contributor
timestamp: January 11, 2014, 08:56:37 pm
content: Can you use the CAC8X (DropSens - Cable Connector for format 8X Screen-Printed Electrodes)?Or perhaps you're trying to do something like this?"CheapStat: An Open-Source, “Do-It-Yourself” Potentiostat for Analytical and Educational Applications "http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0023783]http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0023783If the sensor you are using has a standard pin pitch then you can use an edge connector socket (similar to the type used in PCs for PCI cards - there are a lot of standards for industrial use too)If potential differences due to different materials a problem?If you're making your own "jig" to mount the sensors in you can just buy sockets, or perhaps pins:http://www.te.com/catalog/pn/en/925590-4http://www.digikey.com/product-search/en/connectors-interconnects/backplane-connectors-contacts/1442674?k=silver%20contact

author: tasos987
author_rank: Newbie
timestamp: January 11, 2014, 10:11:44 pm
content: Perhaps there :http://www.molex.com/molex/products/group?key=micro_connectors&channel=PRODUCTSYou could find something to fit on your pins. They have good & detailed documentation for their products.
manoman.sqhill.com? - Page 1
Forum section: electronics / projects

author: staze
author_rank: Frequent Contributor
timestamp: May 05, 2016, 08:30:59 pm
content: All,Anyone know what happened to this wonderful manual source? All the links result in forbidden.I mainly ask because I found a copy of Shannon Hill's Tek 2465 manual onhttp://elektrotanya.com/,but it's got an owner password on it, and I really want to OCR the manual. I don't know if it was originally passworded on sqhill's site, or if elektrotanya.com added the password. It's annoying either way, and must be pretty long, because I've got a PDF cracker working on it, and we're up to 9 characters at this point.Thoughts? Help? Maybe Shannon Hill is an eevblog member?

author: Knuckx
author_rank: Newbie
timestamp: May 05, 2016, 10:48:07 pm
content: Grab qpdf and give it the file with --decrypt as an option (so do qpdf --decrypt inputfile.pdf outputfile.pdf). Providing the pdf is viewable without a password this should remove all restrictions.

author: staze
author_rank: Frequent Contributor
timestamp: May 05, 2016, 11:50:06 pm
content: wow, okay then. Yes, I had qpdf... wonder how the hell it does that...

author: staze
author_rank: Frequent Contributor
timestamp: May 05, 2016, 11:52:36 pm
content: That said... still curious what happened to manoman.sqhill.com... =/

author: edavid
author_rank: Super Contributor
timestamp: May 05, 2016, 11:55:34 pm
content: Shannon found out the hard way what "unlimited transfer" means, so he moved his manuals to Google Drive.HPhttps://docs.google.com/folder/d/0B7w5p5pSKM5gVnVPQzhhOGZUQ1ETektronixhttps://docs.google.com/folder/d/0B7w5p5pSKM5gRFhTY2V0SlNSRVEDatabookshttps://docs.google.com/folder/d/0B7w5p5pSKM5gc1VrTjBuOFZIX1U

author: staze
author_rank: Frequent Contributor
timestamp: May 05, 2016, 11:56:46 pm
content: oh, cool. =)

author: Knuckx
author_rank: Newbie
timestamp: May 06, 2016, 07:08:07 pm
content: Quote from: staze on May 05, 2016, 11:50:06 pmMagic!Actually, all protected PDFs are encrypted, with the restrictions held in the encryption container. Encrypted PDFs with no view password have the encryption key in plaintext in the container so you can read the file. If you decrypt the file with the plaintext key, then save the contents of the container, it implicitly removes the restrictions, as the encryption container is gone, taking the restrictions with it.It works with view passworded files as well, providing you know the view password (pass it to qpdf with --password).
Manson EP-611 mod (well trying to) - Page 1
Forum section: electronics / projects

author: Harvs
author_rank: Super Contributor
timestamp: January 21, 2013, 01:32:33 pm
content: I had a bit of a thought this even, to convert a couple of Manson EP-611 power supplies (aka Dicksmith Q1770) to having a programmable voltage and current set point.I thought it'd probably be pretty easy, I could re-use some circuit blocks from my eload design, and even most of the software modules.I could only find a schematic for an EP-925 online but I assumed it'd be pretty similar. So I devised a straightforward plan for where I could mod the circuit.I opened it up... And errr... Where's all the parts?Seriously I opened it up expecting a LM723 as in the 925, but seriously the only IC on this thing is quantity one dual op-amp. A hand full of to-92 bjts, more diodes than you can poke a stick at, a tap changing relay, and the power transistors.So... ummm... not really sure I want to touch this mess of bodge connections. Maybe I'll just put the screws back and pretend I never opened it.Edit: Does anyone have a schematic for this thing?
Mantis Elite Cam HD - 60 FPS 1080p/4K Conversion - Page 1
Forum section: electronics / projects

author: andrew.perrong
author_rank: Newbie
timestamp: October 05, 2019, 01:53:08 am
content: Hi there.It's well established that one of the best microscopes on the market for electronics work is the Mantis Elite. However, as Dave and others have mentioned, the Elite Cam HD version of the Mantis suffers from a very poor quality camera that is "HD" in name only. The factory camera is unusable because of low frame rate and poor colour reproduction.Over the past few months, I've been working on remedying this issue. After a lot of trial, error, and failures, I've created a one-of-a-kind Mantis Elite Cam. My conversion is complete with 60 FPS video at either 1080p crop or the full sensor size, which is slightly short of 4K, and has much better colour reproduction as it uses a Sony sensor. The case of the Mantis had to be modified to accommodate a USB 3.1 Gen 2 Type C Connector, as well as modifications to the optical assembly to accommodate the new camera and sensor.The conversion is not for the faint of heart, as it requires a good amount of modification and intricate, precision work with the optical assembly. The regular Mantis will not support this at all, so you will either need to purchase an Elite Cam HD or have one available for the conversion. But if you're up for it, you can PM me and I can provide further details about the cost and the process of doing the conversion. If there's enough interest, I think I'll make a little side gig of converting these.I've posted some before/after sample footage with the same board at the below link. I'd love to get any comments or feedback, especially if you think there's a market for selling these.https://drive.google.com/drive/folders/1Bep_ATiz2uT3yo2O9kWPv2yzVrHErYWw
Battery powered Mantis microscope - Page 1
Forum section: electronics / projects

author: nickii
author_rank: Newbie
timestamp: March 02, 2024, 02:38:04 pm
content: Hello,I thought I would share my latest project here. I wanted to get myself a Mantis microscope for a few years now. This time I finally gave in and bought one.As you probably all know, these microscopes can get very expensive very quickly. My solution was to only buy only the head and two lenses (4x and 8x). Everything else I can make on my own.I spent around 1100€ for the head and 600€ for the lenses with caps (always get the caps!). The arm would cost me another 800€ and what hurts the most - the power supply is 100€!!! For a 9V adapter!Naturally, I bought a computer monitor arm. It is way more configurable and only costs 100€ on Amazon. The only thing you have to do is make your own mount for the Mantis head instead of the monitor.But that can be done in 1 hour from some aluminum U profile. I really recommend this solution for microscope mounts to everyone.Regarding the power supply, I carefully disassembled the head and looked at the circuit. It is much simpler than I imagined. There is only a DC power plug, 20 LEDs and 20 current limiting resistors. Their value is surprisingly low. Only 68 ohms. At 9V the current is around 40mA per LED. This did not sit right with me. There is absolutely no need for the current to be so high. The LEDs reach full brightness at 10mA. I am very glad I did not buy their 100€ power supply. I recommend anyone with a Mantis microscope to use a 5V power supply.Another thing I found interesting is that the manual says not to connect the power supply directly to the head. I have no idea why.In the end, I decided to make a battery pack. 4V from Li-ion batteries is just too perfect and clean to pass up. The current trough each LED is around 15mA. And I avoid the cable running down the arm and into the wall. I am using 2 18650 Li-ion batteries, a simple Chinese TP4056 charging module and a switch.Everything is packed inside a small 3D printed enclosure. I had difficulties making it fit nicely around the body but I am pretty happy with the end result. Stl files are attached in a zip archive.It is difficult to capture everything on only a couple images but here it is.Best regards,Nik
manual flying probe - Page 1
Forum section: electronics / projects

author: harerod
author_rank: Frequent Contributor
timestamp: August 03, 2022, 02:41:18 pm
content: I am impressed by this tool:https://blog.acelab.eu.com/pc-3000-flash-spider-board-adapter-how-to-use-it.htmlA quick search didn't show this tool in Acelab's current portfolio.At any rate, I am interested in the mechanical setup only, as a general tool to attach multiple probes to a DUT.My question: has anybody experience with "manual flying probe"s and maybe even some prize and ordering information?Thanks in advance.