hybridfree/eevblog-posts huggingface dataset:
Have some questions about impact/load sensors. - Page 1
Forum section: electronics / beginners

author: ByronKingson
author_rank: Newbie
timestamp: February 23, 2018, 12:12:40 am
content: I was thinking about putting together one of those DDR dance pads. I basically just need a switch to see if a person is stepping on one of the pads or not. My question is, do load sensors still show a reading once they have passed their load rating or will it just stop functioning?

author: Paul Price
author_rank: Super Contributor
timestamp: February 23, 2018, 01:03:30 am
content: You might not need something so sophisticated and costly as a "load sensor" product. You could just make a simple one from two pieces of PC board separated by some foam/rubber with an array of holes. Much more rugged and very cheap. You can substitute thin metal plates to make the contact surfaces even cheaper. Or make a cheap pressure sensor by forming two contacts that will overlap when the item stepped on distorts the original shape and make a connection. Or make a capacitive sensor by a metal sheet/plastic sheet/metal sheet combo that changes capacitance. The possibilities are endless.

author: ByronKingson
author_rank: Newbie
timestamp: February 23, 2018, 01:15:02 am
content: That might work. I wanted to go for one of the thin sheet load sensor in the hopes to avoid damage and keep it reliable over time. but i guess i dont really know how well that will work either.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: February 23, 2018, 04:31:24 am
content: A variation of this may work for you.Edit: I will add that there is a part 2 to the video.
Have tons of 27c020, but project calls for a 27c010. - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: February 08, 2018, 07:58:15 am
content: Will it work if i cut off pin 30 after programming, and double the 27c010 image to fill the missing space on the ROM?

author: BrianHG
author_rank: Super Contributor
timestamp: February 08, 2018, 08:20:45 am
content: No need to cut the pin, just make sure it's tied to GND and you only need to fill the first half.If the pin is tied to VCC, you only need to fill the second half.If the pin is tied to a processor address line, you may need to fill both half with a copy of each other.Do not leave the pin open or just cut. This isn't good for CMOS IC inputs.

author: james_s
author_rank: Super Contributor
timestamp: February 09, 2018, 07:59:02 am
content: Double up the image either way, that will save the effort of worrying about whether the extra pin is high or low. Then you can tie it to either one, or tie it to the adjacent address pin, it will work either way.
Have you ever seen a resistor like this? strong positive tempco - Page 1
Forum section: electronics / beginners

author: Rabbitoose
author_rank: Contributor
timestamp: October 07, 2025, 09:16:51 am
content: I came across a strange resistor and I’m trying to identify what type it is.I measured it with a network analyzer (100 kHz – 100 MHz), and it behaves as a purely resistive element — no noticeable inductance or capacitance.However, it has a pretty large positive temperature coefficient. Its resistance is about 360 Ω at room temperature, goes up to ~365 Ω just by touching it, and easily rises above 400 Ω with a bit of hot air.The color bands read orange, blue, brown, gold, yellow. The first four seem to match a 360 Ω ±5% resistor, but the temperature behavior suggests it’s something different — maybe a metal oxide or some special type used for temperature compensation?Has anyone seen this kind of resistor before or knows what material or type it might be?

author: Doctorandus_P
author_rank: Super Contributor
timestamp: October 07, 2025, 09:58:01 am
content: Carbon composite resistors have very low parasitic properties, because the element is just a slug of the stuff. (But they do have other disadvantages). But carbon composite usually does not look like that. The ones I've seen are straight cylinders.

author: tggzzz
author_rank: Super Contributor
timestamp: October 07, 2025, 10:38:45 am
content: Quote from: Rabbitoose on October 07, 2025, 09:16:51 amWhere exactly?

author: tautech
author_rank: Super Contributor
timestamp: October 07, 2025, 10:39:06 am
content: PTC Thermistor ?NTC are the more common.

author: Rabbitoose
author_rank: Contributor
timestamp: October 07, 2025, 10:56:14 am
content: Quote from: tggzzz on October 07, 2025, 10:38:45 amIt's in a Negative Impedance Converter circuit, used to compensate the geophone coil resistance drift (though NTC are more commonly used)

author: Rabbitoose
author_rank: Contributor
timestamp: October 07, 2025, 11:23:32 am
content: Quote from: Doctorandus_P on October 07, 2025, 09:58:01 amThank you. I did some searching on Google, and it looks like this type of resistor may have a temperature coefficient exceeding 1000 ppm/°C. I’ll continue checking product catalogs to find similar type.

author: gamalot
author_rank: Super Contributor
timestamp: October 07, 2025, 11:33:33 am
content: Some manufacturers use similar color bands on their fusible power resistors.A black 5th band indicates the resistor is inductive, while a green one means it's non-inductive.

author: mtwieg
author_rank: Frequent Contributor
timestamp: October 07, 2025, 02:18:27 pm
content: Fusible resistor would be my first guess, since the TC does not seem strong enough to be a typical PTC (i.e. those used as resettable fuses). But perhaps for this circuit a PTC with a specific low TC is required?I wonder if one could differentiate a fuse (i.e. made of Nichrome) and a thermistor by measuring the R-T curve? Does Nichrome obey the Steinhart–Hart equation....?
... - Page 1
Forum section: electronics / beginners

author: cleaningOut
author_rank: Contributor
timestamp: May 01, 2018, 04:50:42 am
content: ....

author: dmills
author_rank: Super Contributor
timestamp: May 01, 2018, 11:24:58 am
content: Try this one.Q1 is the modulator transistor, biased as a simple emitter follower with the emitter at ~7V, the emitter tracks the modulation input.R4 is just a place to measure the current.C3 decouples the RF from the top of the tank circuit L1,C5 which is resonant at 200KHz.Q2 is the RF transistor run in class C, with D1 serving to provide the return path for the bias current, this is effectively switching with the tank serving to reduce (somewhat) the harmonics generated, in a real sender this would probably be set up for class E or such but not worth doing the maths for this.C1,2,4 are DC blocks, and in reality there would probably be a matching network around C4 to both increase the available power and lower the harmonic content.You will need to change C5/L1 if you change the frequency it is tuned at the moment for 200kHz.Regards, Dan.
Having difficulty finding tips for Weller SP40N soldering iron - Page 1
Forum section: electronics / beginners

author: bigfoot22
author_rank: Contributor
timestamp: February 01, 2023, 01:24:31 pm
content: deleted

author: themadhippy
author_rank: Super Contributor
timestamp: February 01, 2023, 02:58:45 pm
content: Quotehttps://www.rapidonline.com/weller-replacement-soldering-tips-for-spn-series-soldering-irons-560427Uk based so no idea of how much use it is to you

author: uli12us
author_rank: Contributor
timestamp: February 02, 2023, 09:24:11 am
content: Is it possible to drill the hole larger, 6,5 or 6,6 mm is not so unusual or in Australia with letter sizes maybe F or G.
Having issue /w INA125 In-Amp SPICE model in LTspice? - Page 1
Forum section: electronics / beginners

author: comfortcube
author_rank: Contributor
timestamp: August 24, 2021, 12:45:48 am
content: Hello everyone!So I've got an INA125 model in LTspice working fine, and a couple of LM741 models as well. The circuit is shown here:https://imgur.com/gallery/JTcW2qH. I'm trying to see that the two Sallen Key stages formed by the LM741s effectively filter the 30mVp noise riding on top of the 10mV DC that I'm actually trying to get out and amplified through the INA125. Currently the gain resistor on the INA125 is set such that the gain is x4. So I'm expecting close to 40mV DC output. However, instead I'm just getting what you see in the second image in the imgur post. It's just saturating the output at the negative rail.The weird thing is the filter stage and the INA125 separately work just fine! As soon as I put them in the same schematic, I get these issues. What's up?I'm trying to simulate a circuit I've got that involves the INA125 instrumentation amplifier. I'm simulating it on LTspice. I downloaded the SPICE model from the TI page of the devicehttps://www.ti.com/product/INA125. I was at first just trying to make sure the model works as expected, so I have the schematic in LTspice drawn up as shown in the first image on this imgur post:https://imgur.com/gallery/duN5oRJ. The circuit is based on the schematic shown in the datasheet, which is linked at the bottom and is also shown in the imgur post. However, the pin numbers are based off of the SPICE .lib file, a screenshot of which is on the imgur post; unfortunately the numbers don't exactly match the pinout layed out in the datasheet, and it seems a pain to convert all the numbers so they match the actual pinout of the device. Perhaps here is where the problem lies, I don't know.In any case, as shown in the circuit, I've got 1V differential input, and have the gain resistor set to 1Meg, which should result pretty much in a gain of 4. However, I'm pretty much getting the same output on Vout no matter what --> ~14.1V. I have a slight suspicion that there may be something wrong as well with the .lib file, idk. But I'm lost. Anybody got any ideas?INA125 Datasheet:https://www.ti.com/lit/ds/symlink/ina125.pdfImgur Post /w Screenshots:https://imgur.com/gallery/duN5oRJEDIT: Someone commented on the imgur post saying that my input is floating and not ground referenced while the output is. I connected the inverting input to gnd and now the simulation works... I'm confused though --> I thought since this input is differential that such a ground reference wouldn't matter?

author: iMo
author_rank: Super Contributor
timestamp: August 24, 2021, 08:59:11 pm
content: Where is your .asc file with the final schematics?
having issues building a motor driver - Page 1
Forum section: electronics / beginners

author: cold-steel
author_rank: Newbie
timestamp: June 24, 2019, 03:05:37 pm
content: i am using a irf510 n channel mosfet and a 10k pull down resistor in order to control a motor that is connected to the wire in parallel with the diode. it only turn on when i touch the metal which gets it tot turn on and off, or if i connect the gate to the 12v power line.connecting the resistor to the 12v line and plugging the wire on that line or taking it off has the desired effect but it doesn't work when i use the 555 timer output. I'm guessing that the problem might be with the power supplies. the pull down resistor only works on the 12v line.

author: cur8xgo
author_rank: Regular Contributor
timestamp: June 24, 2019, 03:09:20 pm
content: Quote from: cold-steel on June 24, 2019, 03:05:37 pmDraw a schematic?Is 555 output above the IRF510 gate threshold?Do you have a way of confirming your 555 output is working at all?

author: garethw
author_rank: Regular Contributor
timestamp: June 24, 2019, 03:20:31 pm
content: In addition to previous comment, make sure your mosfet is ‘below’ your motor I.e the motor is connected to power and is grounded through the mosfet. This is because you need you gate voltage to be, say, 10v higher than the source. If you put the motor after the mosfet the source is only a few mV lower than the gate and the mosfet won’t turn on fully or at all.Sent from my iPhone using Tapatalk

author: ArthurWozniak
author_rank: Newbie
timestamp: June 29, 2019, 01:12:24 am
content: Hey,Did you connect GND from 7v and 12v together?If you can, try to use push-pull circuit with complementary transistors to drive the MOSFET,Best regards,

author: ptricks
author_rank: Frequent Contributor
timestamp: June 29, 2019, 10:52:43 am
content: I suspect what is happening is the 555 output isn't above the gate threshold for the mosfet long enough to complete the turn on before switching back off, the wave form is probably not a solid 10+ volts but rather a deformed one with just the peaks at close to voltage for the mosfet. Motors have a large in-rush current when they start and with the on/off input of the 555 the mosfet is experiencing a lot of surges + high resistance from not turning on fully which makes it run hot.You can do as suggested and try to drive it with transistors or an easier route would be to use a logic level mosfet .
Having on button actuate to other buttons without losing original buttons - Page 1
Forum section: electronics / beginners

author: ScHAmPi
author_rank: Newbie
timestamp: October 09, 2020, 03:50:12 pm
content: Hi all,I'm quite a noob at electronics so bear with me. I'm thinking of combining a USB 3.0 switcher and a displayport switcher into one i.e. link the buttons so I have only one button to press. Basically create a sort of KVM hackjob. It seems easy enough to solder a button to both devices, but I'm worried about their state going out of sync. I.e. displayport device is set to output 2 while usb device is set to output 1.Is there an easy way to have one button control both but still keep the functionality of the original buttons of each device so I can fix any out-of-sync problems without too much effort? Because unless I'm mistaken if I solder a single button to both boards all three buttons will perform the same function.Another advantage would then be that I can keep the devices tucked below my desk and just bring the button to the top.Basically I'm planning on combining these two:Thanks in advance for the feedback or ideas!

author: atmfjstc
author_rank: Regular Contributor
timestamp: October 09, 2020, 04:03:17 pm
content: These kind of momentary push buttons usually work by bridging a normally-broken contact while the button is pressed. You need a button that bridges two independent, normally-broken contacts at a time (which you can then connect with wires to the corresponding buttons in each switcher); the technical term for this is "double pole". I think you can go on electronics parts sites and use the advanced search to find what you need, using criteria like "double pole", "momentary on".

author: ScHAmPi
author_rank: Newbie
timestamp: October 10, 2020, 11:28:48 am
content: Thanks for that @atmfjstc. That type of switch seems ideal for the job! I've ordered a DPST momentary switch (I just hope it'll be the right one because it seems some of them just have one set of NO and NC contacts which they then call DP). Looking forward to giving it a try.
Having problem with finding BJT Vbase   - Page 1
Forum section: electronics / beginners

author: negativefeedback
author_rank: Newbie
timestamp: April 08, 2020, 08:33:21 pm
content: Hello,I am having trouble with calculating the base voltage of the attached circuit. I tried to do node voltage method but I wasn't succesful. Could anyone help with the calculation?Thanks.

author: Zero999
author_rank: Super Contributor
timestamp: April 09, 2020, 12:21:04 pm
content: Post your working so far.What does the simulator say? Use it to check your working.

author: negativefeedback
author_rank: Newbie
timestamp: April 09, 2020, 12:26:01 pm
content: Hi, I am having problem to setup equations. I cant match simulation results with hand calculations. I am asking how to construct equations for upper and lower loops.Best.

author: Ian.M
author_rank: Super Contributor
timestamp: April 09, 2020, 12:59:58 pm
content: Its not solvable without knowing the characteristics of the transistor. Here's a LTspice SIM that gives a different Vb for each of generic NPN (SPICE default), 2N3904 and 2N3055.

author: negativefeedback
author_rank: Newbie
timestamp: April 09, 2020, 01:10:58 pm
content: we can say general 2n2222 with 0.7VBE

author: free_electron
author_rank: Super Contributor
timestamp: April 09, 2020, 02:03:52 pm
content: An approximation would be to assume the transistor is in saturation and not consider the base current. So you have (24 volts / (3300+1000+330)) * 330 across R3. So Vr1 is 0.7 volt higher than that. You can now find the rest.Of course this will deviate in real life as we did not take base current and setpoint of the transistor into account. But since that is unknown...Chuck it in a simulator.Or is this one of these 'homework puzzles' teacher like to give to their students ? In that case i would do the calculation for a transistor with a gain of 1000000 ( darlington ). it will be pretty darn close -evil grin- if they can't be bothered to specify what transistor then i pick the one that makes my work the simplest .

author: Ian.M
author_rank: Super Contributor
timestamp: April 09, 2020, 02:13:45 pm
content: Quote from: negativefeedback on April 09, 2020, 01:10:58 pmReal transistors don't have a fixed Vbe as it depends on device characteristics, currents and temperatures. If you are going to use a 'kindergarten' level model of a NPN transistor that assumes Vbe=0.7V whenever current is flowing into the base, you'll also need to assume a fixed hFEto make it solvable. 2N2222 hFEusually falls in the range 35 to 300 depending on collector current Ic, device to device gain variation and temperature.free_electron has just posted a nice approach to getting the limiting values as hFEtends to infinity. You *COULD* use that to approximate Ic then plug in numbers from the graphs in the OnSemi2N2222A datasheetto refine your answer.
Having some trouble with tda2822 - Page 1
Forum section: electronics / beginners

author: ajblanco09
author_rank: Newbie
timestamp: January 12, 2016, 03:31:38 am
content: I've been building an amp with the bridge mode of the tda2822 and everything was fine until I turned the volume up, I'm using a smartphone as the input of the amp but when it reaches certain amount of volume the sound collapses, I'm using a 9v 500mA power supply and a 3w 4ohm speaker, I'm using the circuit shown in the datasheet. I thought I could use a class b amp in combination with the tda.. But I don't know which one use or if that's the solution. Thanks!.Enviado desde mi Z812 mediante Tapatalk

author: Zero999
author_rank: Super Contributor
timestamp: January 12, 2016, 08:58:32 am
content: Does the TDA2822 get hot?Have you measured the power supply voltage when the volume is turned up?Perhaps it's overheating or the power supply is being overloaded and shutting down?

author: Audioguru
author_rank: Super Contributor
timestamp: January 12, 2016, 07:28:00 pm
content: The datasheet for the TDA2822 in the 14 pins case shows that it overheats when it dissipates about 1.5W without a heatsink.Your circuit has both amplifiers bridged. The datasheet shows your bridged circuit driving an 8 ohm speaker (not your 4 ohm speaker which draws double the current) with a 9V supply producing an output of 3.2W and dissipating 2.1W of heat which will cause it to overheat and be damaged unless it has a heatsink attached somehow (glued on top?). The heatsink must not be enclosed.The datasheet shows it bridged and driving a 4 ohm speaker with a 6V supply (not your 9V supply that produces much more power) but the curves for power and dissipation are mixed up. It probably produces an output of about 1.5W and dissipates about 1W of heat.Your TDA2822 might have been fried.

author: ajblanco09
author_rank: Newbie
timestamp: January 13, 2016, 03:23:18 am
content: Quote from: Hero999 on January 12, 2016, 08:58:32 amYes, it does get hot but it has a heatsink on top of itEnviado desde mi Z812 mediante Tapatalk

author: ajblanco09
author_rank: Newbie
timestamp: January 13, 2016, 03:31:55 am
content: Quote from: Audioguru on January 12, 2016, 07:28:00 pmHi, I did put a heatsink on top and I also tried an 8 ohm speaker but the results are the same, it is still working btw, I tried a 6v 500ma ps but the only change I noticed is that the performance reduces a little bit, I was going to try to attach a class b amp with a bc637 and a bc640 but I couldn't find the components yet and see what results.Enviado desde mi Z812 mediante Tapatalk
Having trouble making a high power signal generator.  - Page 1
Forum section: electronics / beginners

author: Tylerebowers
author_rank: Newbie
timestamp: April 19, 2020, 06:57:08 pm
content: I have circuit that is using an IRS2453, it is used for driving H-bridges (it includes dead times). The mosfets that I am using are FQA46N15 and they will work for this application. I designed a schematic (the attached image) and built a circuit for it. The problem is that the output is at 60Hz, and I need the output at 28KHz. The data sheet says that the internal oscillator can run in this frequency range on page 7, and it is also based on a 555 timer. The RT and CT values were calculated with the given equation on page 13 of the datasheet.I have two of the IRS2453 ics, so I connected the power to it without anything else connected and the outputs were also at 60hz. This result leads me to believe that I have pins 3 and 4 connected wrong.What could I do to fix this?Links:IRS2453 Datasheet:https://www.infineon.com/dgdl/Infineon-IRS2453D-DataSheet-v02_00-EN.pdf?fileId=5546d462533600a40153567ac42f2814

author: Manul
author_rank: Super Contributor
timestamp: April 19, 2020, 08:05:15 pm
content: If you did not, connect SD pin to COM. Also, does the frequency change at all if you adjust resistor or change 10nF capacitor? 60 Hz is suspiciously same as mains frequency...

author: Tylerebowers
author_rank: Newbie
timestamp: April 19, 2020, 08:55:25 pm
content: I just found out the issue, one of the potentiometers was broken so I just used a different one. Also the SD is connected to com.
Having trouble running LTC2953-1 simulation on LTspice - Page 1
Forum section: electronics / beginners

author: andre123
author_rank: Newbie
timestamp: November 08, 2020, 03:10:02 pm
content: I'm having a hard time in running the simulation for the LTC2953-1 which is a Push Button On/Off Controller IC , it also has other features which i'm not going to use for time being so they are disabled/ not used.Here i am expecting the output (EN) pin to be latched high as soon as the Switch is pressed at pin (/PB) for more than 6.4 seconds (1uF is set to have =~ 6.4seconds). Also i am getting this error which maybe the cause of not getting the IC to work properly..This is a simple illustration on the relation between the push button input signal and the output signal(EN)Schematic and input signal(Blue) output signal (Green) probed, where output is giving a zero ; should latch to high.error messageI would really appreciate if someone would point out what might be the cause of this situation .Note: I've inlcuded in the attachments below the LTspice project file in case someone is interested.

author: Ian.M
author_rank: Super Contributor
timestamp: November 08, 2020, 03:57:35 pm
content: EN is open drain ==> R2 must be a pullup.Also you've got problems with your switch control source V2. I doubt you intended a 1 second risetime! ?? As the chip needs a separate press/hold to turn it off again try V2:Code:PWL(0 0 1 0 +1n 6 +0.1 6 +1n 0 2 0 +1n 6 9 6 +1n 0)Use:Code:.tran 10 startupas you need to see the behavior at 1 sec.The floating node SPICE error can be resolved by setting C1's equiv. parallel resistance to1Gwhich has negligible effect on the circuit but keeps the SPICE engine happy.

author: andre123
author_rank: Newbie
timestamp: November 08, 2020, 07:58:37 pm
content: Thank you for the open drain point. I went ahead and put a 100K pullup and set up the switch as per indicated and now it alive but it nearly instantly works at the first falling edge like there is not delay, any idea what could be the culprit ? I'll dig more in the datasheet maybe i missed something.Thanks again for the massive help, really appreciate it.

author: Ian.M
author_rank: Super Contributor
timestamp: November 08, 2020, 08:07:34 pm
content: I suspect you'll find the sim now agrees with the datasheet.There's no need for a separate 1G resistor (R6) to keep the sim happy. Just right-click C1 and set the Equiv. parallel resistance in its properties dialog to 1G

author: andre123
author_rank: Newbie
timestamp: November 08, 2020, 09:22:03 pm
content: Quote from: Ian.M on November 08, 2020, 08:07:34 pmYes, i overlooked the detail that the delay is for power down only. It now works as advertised. Thank you sir, much appreciated
Having trouble understanding a PSU design. - Page 1
Forum section: electronics / beginners

author: frasdoge
author_rank: Contributor
timestamp: April 30, 2020, 09:53:09 am
content: Hi everyone, I've come across this excellent series from Dave on building your own Lab Power Supply.I think I understand how both the constant current and constant voltage modes work, although when placed in series I don't understand how the constant current generator turns into a current limiter. The CC circuitry suddenly has no effect until the load starts drawing more than the set amount.I've had a go at simulating them individually in LTSpice and they all work as intended, but I'm failing to see the logic behind why this happens.I've noticed the SPICE model only works as intended as well if I simulate the power rails for the second opamp as well which I've attached.

author: stafil
author_rank: Regular Contributor
timestamp: May 01, 2020, 12:14:26 am
content: Blind leading the blind here.But the way I understand it, is by connect the ADJ pin after the resistor, you "measure" the voltage after the voltage drop of the resistor and adjust the LDO output accordingly. The higher the current the more the voltage drop and the less the voltage feed to the ADJ pin.

author: Manul
author_rank: Super Contributor
timestamp: May 01, 2020, 12:59:38 am
content: Not sure if I understand your question correctly. Maybe you have a confusion about ideal and practical constant current source. Ideal current source will rise voltage as much as needed to achieve the set current. For eg. if we have ideal constant current source of 1A, and connect 1K resistor, the voltage will rise to 1000V to achieve that. In practice, constant current circuit is powered by some limited voltage source. So it may reach its limit of voltage output before it reaches set current and effectively becomes a voltage source itself. That is a practical current source. So if output does not draw enough current, CC section goes into voltage "starvation" mode, reaching its maximum possible output voltage and thats it, it stays there. CV is happy to regulate voltage, because it is getting enough input voltage from CC section output. If output is drawing current above CC set current, CC circuit goes out of voltage starvation and starts to work as an actual constant current source. And that causes CV section to go into input voltage starvation so it can not maintain output voltage regulation, so output voltage starts droping. Something like that.
Having trouble with an experiment. - Page 1
Forum section: electronics / beginners

author: etstudent
author_rank: Regular Contributor
timestamp: September 27, 2012, 05:10:47 pm
content: This is gonna be tough to explain without you knowing or seeing my piece of equipment I'm doing experiments on, but I'll try my best. This piece of equipment is about the size of a small briefcase. It has a DC power supply, logic indicators with 4 LED's W through Z. It has a clock generator with 1 HZ and 1KHZ switch clock+ and clock- hookups. It has a "connection block", a interface block, logic switches that go between NOT-A and A, NOT-B and B. It also has 4 data switches labeled SW1 through SW4. If you want to Google the piece its the Model XK-200 Digital trainer. Maybe there are pics of it somewhere.Ok here is the first experiment issue. Its a RELAY operation. Determine how a relay is used to switch power between 2 circuits. The problem, the RELAY they sent is different than the book, I think messing up the wiring contained in the book. They sent me this RELAY HLS-4078 DC-5V. Its supposed to switch one LED on and then off turning on another. I'm getting nothing, no lit LED, no change in LED lights, nothing. I understand this is tough, because you don't have the equipment, but any help I will appreciate BIG time. I'm sure you guys have worked with this RELAY, so maybe you can help.Here is something awesome, just putting my hands on this stuff, the RELAY's, the capacitors, the resistors is helping me understand circuits better, if that makes any sense. Finally all this stuff I learned about in theory, comes to life. I really LOVE this stuff. I think i will be a kick @ss ET, if I can pass this experiments part of this program. Thanks again for any help. SORRY for the LONG posting.

author: Bored@Work
author_rank: Super Contributor
timestamp: September 27, 2012, 05:17:40 pm
content: Plug HLS-4078 into Google, download that thing called datasheet, read it, and look for the pin layout. Use it to wire you circuit correctly.

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 27, 2012, 05:40:05 pm
content: The HLS-4078 looks quite standard to me, what is the model used in the book?If - after googling the datasheet - you still can't get it to work explain how you connected it.You should hear it clicking when it is supposed to switch, if not you are probably not using the correct pins for the coil.

author: etstudent
author_rank: Regular Contributor
timestamp: September 28, 2012, 03:03:08 am
content: Sorry was out all day, thanks for the advice. I will try those suggestions today or tomorrow.
Having trouble with mesh analysis q? - Page 1
Forum section: electronics / beginners

author: Alex30
author_rank: Regular Contributor
timestamp: August 27, 2014, 06:59:46 am
content: Just trying to work out the mesh analysis on this circuit and using ltspice to check my answer but I'm getting conflicting answers and I'm not sure whats going on.So far I have the following three equations:(120+150+330)*I(1)-150*I(2)-330*I(3)=20-150*I(1)+(180+150+220)*I(2)-220*I(3)=15-330*I(1)-220*I(2)+650*I(3)=0substituting into matrix A:550 -150 -330 | 20-150 550 -220 | 15-330 -220 650 | 0Det(A)=73705000Det-I1(A)=8733500Det-I2(A)=7131000Det-I3(A)=6847500Using Cramers ruleI1=8733500/73705000=0.118AI2=7131000/73705000=0.097AI3=6847500/37305000=0.093ABut when I probe the circuit on LTspice I get I1=40.7mA I2=9.1mA and I3=17.6mA??Any help is greatly appreciated!

author: Alex30
author_rank: Regular Contributor
timestamp: August 27, 2014, 09:28:47 am
content: Aha, I had my signs wrong. I wasn't taking into account my assumptions about direction of current.Correct expressions are:600i1+150i2-330i3=20150i1+550i2+220i3=15-330i1+220i2+650i3=0Cheers
HC-05 won't stop responding - Page 1
Forum section: electronics / beginners

author: DuRoble
author_rank: Newbie
timestamp: June 05, 2017, 03:07:10 pm
content: Hello everyone,I "just" started using the HC-05 Bluetooth module and I'm having some issues. Unfortunately no one else seems to have this issue :/ If I enter AT mode (38400) I can send almost all AT commands and I will also get an answer from the module. Or to be more precise I get an unlimited amount of answers until I press Enter a second time.I tried different commands, different settings, different serial terminals and also different HC-05 modules from different suppliers. I keep seeing the issue. There might be a super easy solution to this but I was not able to find itAlso if I type AT+NAME? and hit Enter the module does not respond and simply resets itself...Please let me know if you have any ideasThanks for your help!Robin
HC-SR04 untra sonic sensor help - Page 1
Forum section: electronics / beginners

author: MrOmnos
author_rank: Frequent Contributor
timestamp: December 12, 2015, 08:16:40 am
content: I am going to use 6 ultra sonic sensor for my project. These sensors can used with either 3 pin or 4 pins. I just wanted to know if there's any difference in performance between using both Echo and Trigger pins and using just the echo pin? I want good accuracy for my project.

author: andre_teprom
author_rank: Regular Contributor
timestamp: December 13, 2015, 12:03:18 am
content: Not clear this question.Both pins has different purposes, one refers to output, other to input.
HC-SR501 Help  - Page 1
Forum section: electronics / beginners

author: Fisher77
author_rank: Regular Contributor
timestamp: December 01, 2016, 03:37:41 am
content: I bought some of the HC-SR501 PIR's trying to build some motion lights. I am trying to run 25 green led's with this through a 2N2222 transistor. All the led's have a 150 ohm resistors. The ground for the led's is connected to the collector, emitter to ground, and base to the output of the HC-SR501 with a resistor. I have no trouble getting the led's to switch on when feeding the base of the transistor 3.5 volts. I am trying to run this on 6 volts 4 C batteries. I have tried it with varying voltages to no avail. So far all this has done is blink about every 30 seconds or less. I have tried 4 different HC-SR501's, all with the same results. Can anyone tell me what I am doing wrong here?
HCF4013 Pain Test mixed results - Page 1
Forum section: electronics / beginners

author: JonPyro
author_rank: Regular Contributor
timestamp: March 04, 2018, 08:14:24 pm
content: Hi All,So I was sitting at my bench today working on a latch circuit from the HCF4013 (http://www.st.com/content/ccc/resource/technical/document/datasheet/b7/dc/2d/40/2b/31/4c/b5/CD00000362.pdf/files/CD00000362.pdf/jcr:content/translations/en.CD00000362.pdf) and as per usual i started with a simple RC circuit on the reset so i knew when it powers on it resets Q low.....obviously i worked on some values that made the pulse decay quickly to avoid it lingering between the VIH and VIL thresholds.But then I thought to myself, why not try and make it hold between the threshold values and see how the chip holds up to any oscillations on the outputs which i assumed would happen as the reset is not being held either high or low.Below is a trace, yellow on the Reset input and then blue on Q output:As you can see, horribly slow charge lasting around 50s but nothing much of interest until we reach around 6V and you can see a blip on the output, zooming in we see this:6-5V is in the lower end of the no go area on a 12V supply so could this be the oscillation I am trying to achieve? This is scaled on the 20mV range so this is tiny tiny tiny where I would have expected it to be a couple of volts at least.For me this is surprising as I was always taught running a long time in this range can cause certain death but in this case I hardly call a 100mv or so causing many problems. Or maybe this is not what I am looking at at all?I have triggered this a few times just to make sure its not some weird noise but it consistently appears in the same place and same amplitude.The datasheet doesn't show this circuit having any real protection against idiots like myself doing this so I was expecting it to be a much bigger more obvious problem....the input shows a buffer but not a schmitt trigger which was my first thought to why it is so suppressed.
HD44780 VFD displays? - Page 1
Forum section: electronics / beginners

author: ice595
author_rank: Regular Contributor
timestamp: November 29, 2016, 02:54:40 pm
content: Anyone here have pixel response time problems with HD44780 compatible LCD modules before?Whenever I try to scroll some text on screen it look really bad. (my LCD modules are the white font on blue backlight type, not sure if that makes a difference)After some googling around for some HD44780 compatible VFD display modules and I found this ->http://noritake-vfd.com/discount.aspxAnyone had experience with these kinds of displays before?Since they're HD44780 compatible they can be used as a direct replacement for the LCD modules right? (I don't mind that they're 20x2 characters)

author: bktemp
author_rank: Super Contributor
timestamp: November 29, 2016, 03:05:39 pm
content: Quote from: ice595 on November 29, 2016, 02:54:40 pmBlue-white LCDs have the worst response time. Animations look much better on Black-white or green-black type LCDs.VFDs have a much faster response time, only limited by the display scan rate. You could also look at OLEDs. There are some 44780 compatible OLED modules.
HD61602 LCD driver READY pin? - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: December 25, 2017, 02:19:33 am
content: I've got this old (Sanmina1 MV 1) LCD module I salvaged from an old II Morrow Tigershark Loran of some sort.It uses two Hitachi HD61602 chips and a 74HC00 (two NAND gates are connected to the CS pins of the HD61602s).http://www.pacificdisplay.com/ics_app%20notes/hitachi/HD61602-61603.pdfIn the datasheet is says this about the READY pin...READYNumber of lines:1 / NMOS open drain output / Connected to: MCUWhile data is being set in the display data RAMand mode setting latch in the LSI after datatransfer, low is output from the READY terminalto inhibit the next data input.There are two modes: one in which low is outputonly when both of CS and RE are low, and theother in which low is output regardless of CS andRE.3. READY output modeDetermines the READY output timing.After a data set is transferred, the data is processed internally. The next data cannot be acknowledgedduring the processing period. The READY output reports the period to the MPU. The timing when theREADY is output can be selected from the following two modes:a. READY is mode always available (Figure 12).b. READY is mode available by CS and RE (Figure 13).QUESTION?Is this pin simply there to give the MCU a warning that it should only send data when it sees this pin is high?I know this is ancient hardware but I'm just seeing if I can figure it out.

author: Gabriel
author_rank: Regular Contributor
timestamp: December 25, 2017, 10:19:38 pm
content: Yes, basically that how I would interpret it as well. I thinks it's just a BUSY indicator that goes low when it is busy. Just make the micro wait until it is high then send the data.Gabriel
HDAudio jack on pc cases - how to to tell which one is the correct one - Page 1
Forum section: electronics / beginners

author: amateur_25
author_rank: Regular Contributor
timestamp: May 08, 2014, 08:12:27 pm
content: I basically clumsily tripped over my headphone cable which was plugged into the front audio panel on the case. This caused the jack to split in the middle. I want to replace the jack. Am told HDAudio connectors have special way of sensing if something has been plugged in. Now I used the ones we had lying around but it caused the auto sensing to go haywire i.e. it was cycling between being detected and not detected! I know you can turn off the sensing but I dont want to because it's useful feature to have. For example when you watching a horror movie at 1AM. Does anyone know where I can get these and how to tell they're the right type

author: HalfSpace
author_rank: Regular Contributor
timestamp: May 10, 2014, 11:38:39 pm
content: Hi amateur_25,A picture of the broken jack would help as there are many different pin configurations for these jacks.HalfSpace

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 10, 2014, 11:42:49 pm
content: The chips they use to drive the connectors typically have extra circuit functionality to detect when a load is connected.I have never seen any difference in the connector itself.Of course, HalfSpace is absolutely correct, discussing this without good photos of the connector in question is nearly meaningless theoretical babbling.This will never succeed as a generic question.

author: Rigby
author_rank: Super Contributor
timestamp: May 11, 2014, 02:35:39 am
content: Most of the audio jacks I've seen use a simple switch that closes when the appropriate plug is inserted. Detection relies on good connectivity on the switch, which is usually not enclosed, and thus easily corroded, and good solder joints, which will be questionable after a good tug.
HDMI auto-detect override - Page 1
Forum section: electronics / beginners

author: edy
author_rank: Super Contributor
timestamp: August 13, 2015, 02:04:28 pm
content: Hi everyone,My friend bought an MBOX android media player and it is plugged in to a TV at the office waiting room. Normally people can switch inputs and choose to either watch regular cable TV, or the HDMI (MBOX) that has some office ad looping.The problem is, when people watch TV, the MBOX goes to sleep as it stops detecting the HDMI monitor. So after a few minutes when they flip input on remote back to HDMI they can't see anything from the MBOXNow I have a feeling this may also have to do with a Y-splitter HDMI. The MBOX HDMI out is split to another TV as well. The main thing is, once someone stops watching the MBOX (either by changing their TV input to cable or turning off the TV) on one or both waiting room TV's, it looks like the MBOX doesn't detect an active monitor display on the HDMI and goes into sleep mode, and there is no "force output" anywhere in the settings menus.Is there any splitter or "dummy load" type device or adapter that will trick the box into thinking a monitor is still there so the output remains active on the MBOX all the time? That way, either one or both TV'S in the waiting room can flip to the MBOX video at any time during the day and it will still be playing.

author: wraper
author_rank: Unknown
timestamp: August 13, 2015, 02:15:29 pm
content: Well, you could try attach a 1k resistor between hot plug and 5V pins of HDMI wire. In this way it won't see that TV got disconnected. If that is not enough, you can also attach 24Cxx eeprom with TV EDID programmed to DDC data and DDC clock pins (and cutting those wires going to the TV) and powered from 5V pin.

author: edy
author_rank: Super Contributor
timestamp: August 13, 2015, 02:26:47 pm
content: Thanks. Is there no dongle that will do this that is already made? I don't think she is technical enough to do that and I'm not nearby. If not, perhaps a cool project for someone to sell either kits or start making such an adapter/dongle. I will have to hack a spare HDMI cable if I don't find something and send it to her.

author: andtfoot
author_rank: Unknown
timestamp: August 13, 2015, 02:37:28 pm
content: I don't know for certain it would work, but my first guess would be an EDID minder of some sort. Here is a commercial version; dunno if there is a consumer grade equivalent:http://www.krameraustralia.com.au/products/model.asp?pid=1700&sf=524&pname=VA-2H

author: Teledog
author_rank: Regular Contributor
timestamp: August 13, 2015, 02:39:55 pm
content: I've got an Mbox (MXIII) and it doesn't "sleep" when the TV/HDMI is changed to the cable box, even if left for hours on end.Might check the settings on the unit & make sure a screensaver/sleep mode isn't enabled.Also, is the HDMI mode set to autodetect?

author: wraper
author_rank: Unknown
timestamp: August 13, 2015, 02:41:59 pm
content: Quote from: edy on August 13, 2015, 02:26:47 pmThere are, but they aren't cheaphttp://www.amazon.com/Aten-VC080-HDMI-EDID-EMULATOR/dp/B00FQQFTGIhttp://www.amazon.com/ConnectPRO-TMDS-KITU1-Video-Ghosting-Emulator/dp/B007JNYM6Y
HDMI -> eDP board?  - Page 1
Forum section: electronics / beginners

author: dogman
author_rank: Contributor
timestamp: May 30, 2017, 03:27:23 pm
content: HiI need HDMI->eDP board, both for 30-pin and 40-pinAnything like that? (could be two different board)I have multiple different displays to test, and I don't know ahead what are their modelsThanks
hdmi to vga or other analog format - Page 1
Forum section: electronics / beginners

author: marcosgildavid
author_rank: Contributor
timestamp: August 02, 2011, 09:38:10 pm
content: Hi,does anybody know of an easy method for converting an HDMI signal to an analog format (VGA,SCART,S-VIDEO)?Thanks in advance,MD

author: IanB
author_rank: Super Contributor
timestamp: August 02, 2011, 09:48:32 pm
content: Quote from: marcosgildavid on August 02, 2011, 09:38:10 pmThere is no easy way, unfortunately. The HDMI digital signal is encrypted when it comes from HD sources and there is no way to get the raw video data out of it without decrypting it. There is a box you can buy that will generate the RGB signals for you, but it costs ~$200. Cheap, easy or home brew solutions don't exist unless you are content with standard definition signals.

author: marcosgildavid
author_rank: Contributor
timestamp: August 03, 2011, 08:41:23 am
content: Thanks for the reply.I've found these on DealExtreme. They seem quite cheap:http://www.dealextreme.com/p/hdmi-to-vga-video-converter-71816http://www.dealextreme.com/p/hdmi-to-cvbs-video-converter-81278What would be easier to sample, VGA or CVBS?I'm thinking CVBS because of the diferent resolutions for the VGA. Right?
Headphone output straight to amplifier input? - Page 1
Forum section: electronics / beginners

author: ajblanco09
author_rank: Newbie
timestamp: April 29, 2018, 10:14:10 pm
content: Hello.So, a friend of mine had this bluetooth headphones that had one of the drivers broken, so he gave them to me. I was planning to hook them up to a test amp I have, but I don't know if I can just connect the output that goes to the headphones to the input of the amplifier, does it affect in any way the little built-in amp of the headphones?The headphones brand/model is Mpow/Swift and the amp is a bridged tda 2005

author: rhb
author_rank: Super Contributor
timestamp: April 30, 2018, 12:15:01 am
content: Find out the impedance of the output and the input, Make a resistive pad so that the two match. I'd expect that you need a smallish resistor across the headphone output and a larger resistor in series with the amp input. An aux input will probably work fine this way. The headphone output probably won't have enough output to drive a power amplifier external preamp input.Most "line in/aux" inputs are around 30-50k. If the headphone transducers are say 2k then you want a 2k resistor across the headphone amp output and a 48k resistor in series with the amp input. Strictly speaking, you should do the algebra so that the parallel combination of the headphone load and the series resistor and input impedance matches the headphone amp and vice versa.