hybridfree/eevblog-posts huggingface dataset:
10A Buck Converter - RC Sevo's - Page 1
Forum section: electronics / beginners

author: Docara
author_rank: Regular Contributor
timestamp: August 13, 2018, 07:49:27 am
content: Hi,I'm just looking into the feasibility of driving a couple of RC Servos from an automotive source and would like some advice.First off the Servos will be either 7 or 8.4V and have a stall current in the range of 6-8A. And the Power cables would need to run approx. 2-3m.Now I have only ever needed linear power supplies up to 2A so I've used our old friends the 78xx series. It is tempting to buy one of the multitude 10A+ Buck converters from our favourite auction site, but I don't know the implications are of using Buck converters with reference noise etc to surrounding equipment and to the electronics on-board the servos themselves - not to mention the long-term reliabilityThe alternative is to trawl through datasheets and use manufactureres application circuits to knock up a circuit without knowing good PCB layout practices or experience in this area.Your thought would be most welcomeThanksMatt

author: AustinR
author_rank: Newbie
timestamp: August 14, 2018, 01:21:57 pm
content: Reliability is component-specific, so I cannot comment on the longevity of using specific buck converters long-term.However, I can comment a bit on controlling output ripple. Without knowing the specific application or requirements, I don't think you'd have to worry about servo issues too much, but using a capacitor on the output side of the buck converter should reduce how much ripple your servo is seeing.I found a decent video on youtube covering this here:https://youtu.be/G-Llhy2ViUYHope it helps!
10GHz Video Transmitter? - Page 1
Forum section: electronics / beginners

author: Corrosive
author_rank: Newbie
timestamp: July 19, 2015, 09:34:00 am
content: Hello all, I'm currently trying to build an amateur tv transmitter using a 10ghz microwave doppler module such as this onehttp://www.amazon.com/SMAKN-Microwave-10-525GHz-Doppler-Detector/dp/B00FFW4AZ4I have managed to modulate audio over this module without any issue however I've never worked with analog video before. I'm looking to hopefully take a composite video source, amplify it with a transistor and then use that to drive the module modulating it on the 5v input pin.Thus far I haven't had much luck, I have managed to get it to transmit on the 10ghz ham band and down convert it with an lnb, sure enough I can pick it up on channel 60, 40, etc. What I see is a black screen while transmitting telling me I have a working carrier frequency.If anyone is interested here is my attempt:Is it possible to modulate video with one of these?EDITI found this in an old magazineNot sure if this will work on this module or not as it's not a gunn diode, but I'll give it a chance if I can salvage the needed components and post back here if it works.

author: SL4P
author_rank: Super Contributor
timestamp: July 19, 2015, 07:36:13 pm
content: The black screen is encouraging but I think I'd look at the TV input with a scope, to see how the sync is formed, and it will also give you a better view of what your mod/demod is achieving.I'd also careful where I point that 10Ghz emitter, unless you already have enough children.

author: Dago
author_rank: Frequent Contributor
timestamp: July 19, 2015, 07:53:37 pm
content: Quote from: SL4P on July 19, 2015, 07:36:13 pmEmitters like this are used in supermarket door openers... It will do absolutely nothing to you even if you sleep with it in your underpants. The transmit power is in the range of 0 dBm (1 mW).

author: SL4P
author_rank: Super Contributor
timestamp: July 19, 2015, 07:56:24 pm
content: Quote from: Dago on July 19, 2015, 07:53:37 pm😉 I'll let you test that theory!

author: BennVenn
author_rank: Regular Contributor
timestamp: July 19, 2015, 08:59:47 pm
content: I believe there is a bit of capacitance inside that module which will severely limit the bandwidth you can pass through it. I assume you are modulating the 5v supply by a few mV? Will be fine with audio (although attenuated) but trying to push through 5mhz might be troublesome. Sync pulses to reconstruct the frame should make it through OK though any video you do get into the transmitter will look pretty rotten on its way out.Maybe remove the decoupling caps in the doppler unit, but it may not oscillate after...

author: Corrosive
author_rank: Newbie
timestamp: July 20, 2015, 12:14:17 am
content: Without the caps I did run into an issue with oscillation, I have no idea what the bandwidth capability is on this thing unfortunately.I do have a scope but it's only a 10mhz model, not sure if it'll work for this application or not.
10K 2W sliding Potentiometer (pot) for a project... - Page 1
Forum section: electronics / beginners

author: 1974mcd
author_rank: Newbie
timestamp: May 01, 2020, 05:05:08 pm
content: Hi humans(I`ve just registered and the machine had at least 3 ways to be sure that this guy was an human, so you are humans also certainly)After a lot of effort to find a 10Ksliding pot capable of handling 2w for my project of a tig welding foot controler without any positive result, i trust this community to clarify me: Are the 10K W sliding pots more rare than unicorns or my search for one of this things has been badly done?Anyone has a reference, or a source for this kind of pot?The other option to build the foot controler is with a rotary pot actuated by a mecanical way to transform linear motion in rotational movement, i`d like to find a more natural way to go from almost no resistance to the 10k, and a sliding pot is as close to that dream as it gets...Any help will be welcome
10k Potentiometer fast question - Page 1
Forum section: electronics / beginners

author: Dellyjoe
author_rank: Regular Contributor
timestamp: June 25, 2013, 05:36:35 pm
content: hello everyone im just about done my project i have two things to wire up and i don't know which two are the cold and which one is the hot.i know for photometers you have two cold and one hot.here is the data sheet that i found but it doesn't tell me anything.http://octopart.com/datasheet/evu-e2af25d14-panasonic+-+ecg-573536-13329483i have # 3

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: June 25, 2013, 05:53:44 pm
content: resistors like that do not have a polarity

author: Dellyjoe
author_rank: Regular Contributor
timestamp: June 25, 2013, 05:56:01 pm
content: Quote from: Galaxyrise on June 25, 2013, 05:53:44 pmwow i feel sillythanks for the info

author: Mr Smiley
author_rank: Frequent Contributor
timestamp: June 25, 2013, 06:04:46 pm
content: Centre pin will be the wiperIf you want increasing Vout (centre pin) moving in a clockwise direction, looking from the front, Vlow goes to the left pin, Vout ( with respect to the left pin, Vlow ) comes from the middle pin and Vhigh goes to the right pinIf you want decreasing Vout (centre pin) moving in a clockwise direction, looking from the front, Vhigh goes to the left pin, Vout ( with respect to the left pin. Vhigh ) comes from the middle pin and Vlow goes to the right pin

author: Dellyjoe
author_rank: Regular Contributor
timestamp: June 26, 2013, 01:33:02 pm
content: Quote from: Mr Smiley on June 25, 2013, 06:04:46 pmThank you Mr smiley i found that out by playing around with it, but thanks again for letting me know if i didn't do that
10uf tantalum capcitor adxl375 - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: January 20, 2015, 09:49:29 am
content: 1. Adxl375 specifically mentioned about using 10uf tantalum capacitor on Vs.2. What the reason for that?3. What if I use 10uf ceramic for that.I have read on internet thet ceramic has below drawbacks:1. Aging2. Voltage coeff3. Piezeo noise4. Flex crack (most severe)After reading I guess since adxl375 is used for measuring accelration so most dominating reason to use 10uF tantalum will be piezo noise. Is it right?But along with 10uF tantalum, datasheet specify to use 0.1uF ceramic also, which may go opposite to my above reason.I want to know what exactly the reason for using tantalum here.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 20, 2015, 08:58:21 pm
content: Tantalum provides supply damping due to ESR. An acceptable substitute may be a ceramic capacitor of the same value, in series with a chip resistor of a few ohms (to replace the internal ESR of the tantalum).Exact values depend on what else is connected to the supply as well.Tim

author: wraper
author_rank: Unknown
timestamp: January 21, 2015, 02:18:08 am
content: Quote from: T3sl4co1l on January 20, 2015, 08:58:21 pmFew ohms would make it more like electrolytic cap ESR, not tantalum. Unless there is ceramic capacitor unfriendly LDO nearby to this capacitor (low track resistance), no issues with using ceramic as it is. If going to use Y5V or Z5U type, do not forget that they change capacitance drastically with temperature and applied voltage. X7R is far from ideal too, especially when applied voltage is more than half of rated, depends on actual capacitor model though.
1:1 Transformer Winding Confusion - Page 1
Forum section: electronics / beginners

author: made2hack
author_rank: Frequent Contributor
timestamp: April 04, 2017, 10:28:38 am
content: Hello all,So I am again confused as to the winding of my Isolation transformer. The transformer will be a 1:1 Isolation transformer.Assume the following - Max Load 2A (both primary and secondary) ( In reality, the primary will probably see 2.1 A - considering 95% efficiency).I am using 0.9mm diameter (AWG 19) magnet copper wire. This wire has 26.41 Ohm / km. I've tentatively calculated that I will need approximately 110 Meters of wire on each winding. So, as a result, total copper resistance will be on the order of 2.9 Ohms on each winding (Let's approximate to 3 Ohm for now).What is my voltage drop? Is it V = IxR ? Is it V = IxIxR ? (As is in Power / Copper Loss). Do I drop 6V per winding? Or do I drop 12 V per winding? I know technically in AC you use E=IxZ but I don't have the data or patience to calculate Impedance and what not.Questions:1 - Where do I account for voltage drop? In primary? In secondary? Both since it is 1:1 winding?2 - Do I care about Copper Loss or have I taken care of copper loss in the voltage Drop?A similar sized transformer (approx 300VA - 350VA) from the manufacturer where I got my winding states full load copper loses of either 23.5W for the 300VA or 28.6W for the 350VA. If I am dropping 6V per winding, my copper loss will be 18W per winding or 36W total ? If I am dropping 12V per winding, my copper loss will be 36W per winding or 72W total ?Such is my confusion.

author: MagicSmoker
author_rank: Super Contributor
timestamp: April 04, 2017, 03:02:55 pm
content: I already answered your question about voltage drop in the other thread you started.... I also addressed the issue of one of the AC reactances that affect transformer performance: leakage inductance.Quote from: MagicSmoker on March 30, 2017, 02:50:23 pm

author: made2hack
author_rank: Frequent Contributor
timestamp: April 04, 2017, 03:16:23 pm
content: I think I missed it. But it's starting to make sense now. Thanks
12-0-12 500mA transformer enquiry  - Page 1
Forum section: electronics / beginners

author: vis5254
author_rank: Contributor
timestamp: May 06, 2019, 06:33:48 pm
content: This might be the silliest thing asked ever , but i just have a lack of clarity . ie , I've 12-0-12 500mA step down transformer. if I provide 12v ac voltage parallel to 10 ohm resistor , theoretically ohms suggest i would get 12/10 = 1.2A .. Do I ?? practically ??will my transformer current rating might affect this situation ?I was planning to generate 1 or 2 A ac current for current sensor testing !

author: bob91343
author_rank: Super Contributor
timestamp: May 06, 2019, 06:45:14 pm
content: You would be overloading the transformer. It can deliver 12 Volts at a half ampere; any more load will take it beyond its ratings. You need a bigger one.

author: iMo
author_rank: Super Contributor
timestamp: May 06, 2019, 06:51:59 pm
content: You will get 12Vrms with 24ohm resistor wired to 12V--0 terminals.You will get 24Vrms with 48ohm resistor wired to 12V--12V terminals.
12-220V 50Hz Power Inverter - Page 1
Forum section: electronics / beginners

author: johnnyblaz
author_rank: Newbie
timestamp: April 12, 2017, 09:30:08 pm
content: Hi there. I was going through this inverter circuit and I couldn't fully understand the circuit. As far as i figured out the CD4047 is used to generate the 50Hz PWM/square wave signal and the transformer is used to step up the voltage to 220V but what is the purpose of the LM324 ICs and 2N3055 & C1061 transistors? Any help would be appreciated. Thanks

author: David Hess
author_rank: Super Contributor
timestamp: April 13, 2017, 12:30:44 pm
content: That is a very poor design.The LM324 is being used to buffer the output of the clock generator while providing current limiting. 2N3055, C1061, and then a pair of paralleled 2N3055s are configured as a three stage darlington transistor to get enough current gain.Problems with this circuit include high dropout of the triple darlington configuration causing excessive heating and low efficiency, overlap of the output clock causing excessive shoot-through current, and poor current sharing of the paralleled output transistors.

author: johnnyblaz
author_rank: Newbie
timestamp: April 13, 2017, 02:39:21 pm
content: I really appreciate your help.Any suggestions on how to improve this design?Please include component/ic number for the new design.

author: Seekonk
author_rank: Super Contributor
timestamp: April 13, 2017, 05:32:04 pm
content: Get an EG0002 board and a couple fet and you are done for a couple bucks and you have sine wave.

author: james_s
author_rank: Super Contributor
timestamp: April 13, 2017, 06:13:25 pm
content: That looks like it would have been a reasonable design for the 1980s, but these days inverters all use a high frequency DC-DC section followed by a chopper or PWM sine generator, it's a lot more efficient.

author: Audioguru
author_rank: Super Contributor
timestamp: April 14, 2017, 01:11:04 am
content: Does anybody make or use a squarewave inverter anymore?The circuit shown was a 500W squarewave inverter atwww.electyronics-lab.comand it s original horrible design did not work. The circuit you found also does not work because the R and C for the CD4047 are wrong.I corrected the RC on the CD4047 and made a few more improvements about 13 years ago and many of these simple inverters were made and used. The circuit was built with common cheap parts in the Philippines and used by poor people who had no electricity. A battery boy picked up the discharged 12V batteries and replaced them with charged ones every few days.

author: james_s
author_rank: Super Contributor
timestamp: April 14, 2017, 03:14:59 am
content: Most of the inexpensive inverters now produce a "modified sine wave" which is really just a square wave with some dead time inserted. The better ones put out a true sine wave but those are still relatively expensive compared to the common modified sine type.
12-pin micro connector - Page 1
Forum section: electronics / beginners

author: scthom560
author_rank: Newbie
timestamp: March 09, 2025, 12:29:25 pm
content: Hi All.Do you recognize the connector type shown in the photos.I have searched online, used Google lens but not had much luck.I'd really appreciate your help, need it for a project I'm working on.Thanks, Tom.

author: squadchannel
author_rank: Frequent Contributor
timestamp: March 09, 2025, 12:41:25 pm
content: JST GH

author: scthom560
author_rank: Newbie
timestamp: March 09, 2025, 02:45:20 pm
content: Thank you!!!
12 V car voltage stabiliser - Page 1
Forum section: electronics / beginners

author: Unknown
author_rank: Unknown
timestamp: April 20, 2014, 05:12:08 pm
content: Hi, was looking for different 12V car voltage stabilizers, DIY circutry etc. I found this cheap ready to use one from ebay/china wth a so called XL6009I need something like that for input from a car battery and output for a picopsu for a car computer.anybody any experience? well... ordered 2 pieces, will test it and see.http://www.ebay.com/sch/i.html?_odkw=XL6009&LH_BIN=1&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313&_nkw=XL6009&_sacat=0

author: Simon
author_rank: Unknown
timestamp: April 20, 2014, 05:42:08 pm
content: no experience, basically you want a buck/boost converter. I'm going to guess the chip they are based on is one of those and in fact if you read the data sheet you will probably find that it's example circuit is the same as the circuit you are buying.

author: gxti
author_rank: Frequent Contributor
timestamp: April 20, 2014, 05:50:26 pm
content: A boost converter like the ones you linked is only going to be able to increase the voltage, not decrease it. Your car is going to be putting out 14 or more volts most of the time as that is the charge voltage for the battery. The regulator you bought will not decrease that to 12V. Buck-boost or SEPIC is what you want. Or if you're cheap you can get a step-down (buck) module, set your boost module to put out 20V, and feed that into the step-down module to get the 12V you need :-)You probably already bought the picopsu, but they do have an automotive version that is designed for this exact use.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 20, 2014, 06:07:45 pm
content: Yes, as @gxti says, you are in that akward region where your picoPSU wants "regulated 12V", but your vehicle supply could range from 10V to 16V (at extremes). So you need something specifically designed to handle the "hostile" vehicle power environment. Been there, done that, not worth "hacking it" when the proper solution is available.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 20, 2014, 06:49:26 pm
content: Without knowing what kind of battery you are asking about, nobody can help you.Different battery chemistries require different charging regimes.What does "12V DC to 24V battery charger" mean?Does that mean you want to charge different batteries that range from 12V to 24V?Does that mean that you want to charge 24V batteries from 12VDC power source?
12 VOLT 12 AMP HOUR BATTERY REPLACEMENT - Page 1
Forum section: electronics / beginners

author: magnetman12003
author_rank: Contributor
timestamp: May 02, 2017, 07:21:31 pm
content: I wish to replace a 12 volt 12 amp hour battery with a AC TO 12 volt DC power pack. This power pack must light up 9 seven watt 12 volt LED bulbs and NOT '' PULSE'' light them. I already have power units that do just that for some strange reason. What do I look for on Ebay that will do the job and equal what the battery can put out?

author: suicidaleggroll
author_rank: Super Contributor
timestamp: May 02, 2017, 07:24:41 pm
content: You want a 12V supply that can do at least 63W (5.25A). Since this is eBay, you should be looking for a 12V supply that's rated to at least 300W (25A) to account for gross negligence in design and marketing (somewhat tongue-in-cheek, but not really).

author: sokoloff
author_rank: Super Contributor
timestamp: May 02, 2017, 07:29:46 pm
content: In addition to what @suicidaleggroll said, I'd put a multimeter (set to amps) in series with your existing install to understand what the true current draw is. Many "7W LEDs" only draw 3W or so, because of offsetting gross negligence in marketing of LEDs...Figure out what the amp draw is, multiply it by 1.5 and buy a 12V supply of at least that size.If you don't want to go to that trouble (or don't own a meter or don't know how to measure current), buy a 12V, 100W or greater supply. Note that if this is for indoors, a PC power supply is likely to support that. If it's for outdoors, a landscape lighting transformer (one that outputs DC) is likely to meet that spec and be designed to run for hours on end with that type of load.

author: Zero999
author_rank: Super Contributor
timestamp: May 02, 2017, 07:51:11 pm
content: Another option would be to replace the lamps and most likely the holders and wiring (presumably the insulation won't be enough for 120VAC) with mains lamps.If you tried the LEDs on a power supply and they pulsed on and off, it's most likely because the power supply was shutting down, because the current was too high. If you don't want to or it's impractical to replace the lamp, holders and wring, then you need a 100W 12V power supply, as mentioned above. A quick Google search reveals many possibilities.

author: magnetman12003
author_rank: Contributor
timestamp: May 02, 2017, 08:52:33 pm
content: Thanks fellows,I found a 100 watt unit12 volt unit.
12 Volt scooter hack. - Page 1
Forum section: electronics / beginners

author: davelectronic
author_rank: Frequent Contributor
timestamp: December 23, 2016, 08:55:14 pm
content: My Son picked up a freebie scooter in a building. After testing the control pcb is toast. Not wanting to throw £££ at it i was thinking a simple relay to momentary switch hack. As the inital current and start is likley to be huge, i was looking for a soft start idea if possible. Its not worth me throwing pounds at it, but the motor spins up with 12 Volts applied. The SLA is 7 Ah i can't find a rating on the motor, but its been reduced down with gearing. Any ideas to a soft start with a high current relay and momentary switch would be great. Thanks, any ideas appreciated.

author: Gyro
author_rank: Super Contributor
timestamp: December 24, 2016, 10:01:48 am
content: If you're looking for something really quick and dirty (as in your button and relay) then a high power series resistor is the old-time DC motor starter solution. That would limit the stall current but have less effect as motor speed increases and current drops. If you took 1 Ohm as a starting point then that would limit motor current to 12A. Whether you go up or down from there depends on the motor size, mass you're moving, jerkiness etc.It's not elegant, or battery efficient, you need a chunky resistor - it would disipate 140W stalled (less in practice with the thing running). Watch the burn risk! Also not very efficient in battery terms. Got any old wirewound heating elements etc?Your other alternative might be to look on ebay or somewhere for a MOSFET PWM DC motor controller. You probably want to be looking in the 30A range.Edit: Maybe something like this:http://www.ebay.co.uk/itm/1500W-DC-12V-50V-PWM-30A-DC-Motor-Adjust-Speed-Controller-Potentiometer-TE565-/142081401882?hash=item2114b6241a:g:wsYAAOSw6n5Xq2b7I see 10A ones too, but that might be cutting it close, not knowing the motor. Should be an easy job to move the pot external - presumably there's already some sort of hand control in place.

author: orolo
author_rank: Frequent Contributor
timestamp: December 24, 2016, 10:18:38 am
content: You could try modifying a soft-start circuit for audio amplifiers,like this from the excellent Rod Elliot's site,dispensing with the transformer, rectifier and high voltage protection, which would simplify things a lot. The basic idea is setting up a timer which acts upon one relay: normally closed to some power resistors in series with the load, and normally open to a short to the load. The timer keeps the relay closed for a fixed time, the switches to full loading.

author: taustin
author_rank: Contributor
timestamp: December 27, 2016, 07:38:17 pm
content: I know this is a bit more than you were thinking, but it might not be too hard to put together a PWM controller.A POT, microcontroller, and a couple of FETs can do the trick. Sure, there is a little more to it than just that, but once you understand it all it isn't too bad. If you wanted to skip the POT you could simply have the microcotnroller ramp up the duty cycle to help limit starting current spikes.Good luck with whatever you figure out.
12 volt soldering irons - Page 1
Forum section: electronics / beginners

author: dtRCasa
author_rank: Newbie
timestamp: January 07, 2015, 10:26:53 pm
content: It would be good to power a soldering iron from the car batterywhile working on the car, but Weller wants an astonishing $125.90for a 12 volt soldering iron, No. TCP12P. Seems excessive, whycan't i just connect the battery to a $5.00 iron?

author: kingofkya
author_rank: Regular Contributor
timestamp: January 07, 2015, 10:30:50 pm
content: Ohms law....The heater is just a big resistor.

author: Howardlong
author_rank: Super Contributor
timestamp: January 07, 2015, 10:42:48 pm
content: I bought a 12V iron from Radio Shack several years ago, ISTR it was about $20 or so.Alternatively, how about an inverter, or a gas iron?

author: kingofkya
author_rank: Regular Contributor
timestamp: January 07, 2015, 10:53:13 pm
content: Yeah you can get cheap ones because you dont care how clean the power is.http://www.amazon.com/Coleman-PMP200XL-Cup-Style-Power-Inverter/dp/B0006GQA8E/ref=sr_1_6?ie=UTF8&qid=1420671147&sr=8-6&keywords=Coleman+inverter

author: sleemanj
author_rank: Super Contributor
timestamp: January 07, 2015, 11:02:35 pm
content: You can get on eBay unregulated DC irons, some are just typical 936 handles direct wired...and there are proper drivers for various handles which can take a DC voltage down to 12v, add your own handle...

author: theoldwizard1
author_rank: Regular Contributor
timestamp: January 07, 2015, 11:20:04 pm
content: Quote from: dtRCasa on January 07, 2015, 10:26:53 pmI have one of those Weller irons and it is really very nice ! 40W but the temperature is controlled by a standard WellerCurie temperaturetip.

author: Wilksey
author_rank: Super Contributor
timestamp: January 08, 2015, 12:17:20 am
content: I have a Weller gas powered one, and I must say, it works quite well for working on cars etc.

author: dan.soethe
author_rank: Contributor
timestamp: January 08, 2015, 07:20:30 pm
content: I have a butane powered one, I use it all the time when there's no power near by.

author: W8LV
author_rank: Regular Contributor
timestamp: January 09, 2015, 08:01:29 am
content: Butane, but you have to really be careful around all of the carpet and vinyl so that you start one Hell of a car fire.

author: W8LV
author_rank: Regular Contributor
timestamp: January 09, 2015, 08:02:27 am
content: ....so that you DON'T start a car fire... ;

author: amyk
author_rank: Super Contributor
timestamp: January 09, 2015, 01:42:30 pm
content: 12V on a 24V/50W iron will not produce 25W, it will be 12.5W...

author: macboy
author_rank: Super Contributor
timestamp: January 09, 2015, 03:10:05 pm
content: A standard soldering iron doesn't use much power, how about using a small inverter with a 120 V soldering iron?Or try a butane soldering iron. I have one and I really like it. I pulled it out the other day when I needed to do a small job just a few feet away from the bench, instead of using a basic iron. The biggest issue with these is controlling the temperature manually.
1206 footprint - Page 1
Forum section: electronics / beginners

author: Aztlanpz
author_rank: Regular Contributor
timestamp: October 24, 2018, 11:31:48 am
content: Is there a difference from a 1206 footprint for a resistor versus a capacitor?

author: jct
author_rank: Contributor
timestamp: October 24, 2018, 01:01:33 pm
content: I've been using the same footprint for both, no problems experienced during flow soldering.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 24, 2018, 02:32:18 pm
content: There doesn't need to be, no.If there is, it's usually that the capacitor has wider pads, or less pad gap, owing to the less-well-controlled tolerances on the end cap metallization, and the fact that it wraps around. Whereas resistors almost never have wrap-around metallization, but curled around the ends, so there is never a side fillet.Beware of specialty resistors, often low value current sense / shunt types for instance, have differently shaped ends, and will benefit from much less pad gap, or side fillet, or etc. (Also consider heat sinking methods for power resistors, which having somewhat larger pads helps with.)Refer to IPC-7351 (old versions are available free online) for terminology and how to calculate fillets, pad sizes and all that. It varies with lead and package type, but the most common are easy to remember.Tim

author: BocaDev
author_rank: Contributor
timestamp: October 25, 2018, 12:16:05 am
content: QuoteI use the standard 1206 footprint for both. To help our assembly people if the board will be hand soldered, I place a silk screen R or C in the center of the footprint, just large enough to read. Assembly says it does help them to differentiate between a chip capacitor or resistor.
120v AC SSR resistance question - Page 1
Forum section: electronics / beginners

author: smssk
author_rank: Newbie
timestamp: January 20, 2024, 12:09:44 am
content: How do I go about calculating the required resistance to drop 120v AC down to 1.4v DC to drive the SSR in the attached circuit at approximately 15ma?

author: Konkedout
author_rank: Frequent Contributor
timestamp: January 20, 2024, 03:55:18 am
content: 1) Think current instead of voltage. The LED operates at a relatively constant voltage which is small compared to the incoming voltage. It wants to be fed by current; not voltage. How much current do you want? Maybe 10 - 20 mA?? Well OK 15 mA...read below:2) Thinking that way; use a simulator!! LTSpice would work, or I could even simulate it with Excel if I wanted to spend the time. Use the simulator to determine how much current you get through the LED, depending upon input voltage and series resistance.3) I think that the zener D3 will do no good and may well interfere with circuit operation.4) Finally...it may be better to use only one dropping resistor in series with the LED. Use a capacitor at C2 that is rated at 200 or 250 VDC. You might be able to use a 1 uF film type for example. If you do this than you would need one series resistor of about 10K or 12K. But this needs to be (conservative) a 10W rated resistor. Best to use a step down transformer or low voltage power supply to drive the LED. Did you throw away that power adapter from your old cordless phone?

author: johansen
author_rank: Super Contributor
timestamp: January 20, 2024, 04:55:15 am
content: On the order of a .1uf capacitor in series with a bridge rectifier will provide tens of milliamps at constant current. Use the capacitive reactance calculator, put a resistor in series, and a zener to protect the led from power surges.If you just use a resistor then you have to dissipate 10ma times 120vac.You can probably buy 120vac input SSR relays for less than the time to figure out how to build your own.

author: Andy Chee
author_rank: Super Contributor
timestamp: January 20, 2024, 06:23:07 am
content: Quote from: smssk on January 20, 2024, 12:09:44 amHave a read here, particularly the capacitive supply:https://ww1.microchip.com/downloads/en/appnotes/00954a.pdf

author: BillyO
author_rank: Super Contributor
timestamp: January 20, 2024, 09:07:51 pm
content: I would consider a capacitive dropper instead. You will avoid the the dissipation issue.
120v AC to 12v DC Converter Amperage - Page 1
Forum section: electronics / beginners

author: mezmiro
author_rank: Newbie
timestamp: January 23, 2016, 08:21:10 am
content: Hi there!I'm a noob to this forum (and somewhat to electronics design). I have more of a software background, and I'm still getting used to hardware. The project I'm working on now is building an automated coffee roaster. Because roasting coffee is awesome, and everyone should try it!I'm hoping you guys can help me out though.I currently have an Arduino Uno set up with a 16x2 LCD screen for menu display, along with two push buttons and a pot for menu navigation. The issue I'm having is with choosing the amperage I need for a power supply. It needs to supply the above components along with a stepper motor, converting 120vac from the wall to regulated 12vdc. I'm looking at a design similar to the attached photo.I have a few brushless DC motors to choose from in the range of 5v-12v, but how do I decide what amperage my power supply should be to supply this project? I can pull amperage ratings for every other component in this setup, but not for any of the motors. Do you have any advice on this? From what I have read, it's safe to operate components on a power supply that's well over the amperage you need (while not efficient), but it's not safe to go under. Is there a way that I can find the required amperage of these motors?Just for some context, the motor will be spinning a drive shaft attached to a stirring rod with paddles of sorts, which is set on top of a heated pan. The paddles stir up the beans while the heat is applied so that they are heated/roasted evenly. I have the code set up for various speed settings in the Arduino sketch I made, so the load will vary.Thanks for taking the time to look at this. I feel like I have most of this project down but this one is really stumping me.Here are the two motors I'm looking at using right now:https://www.adafruit.com/products/858https://www.adafruit.com/products/324

author: jeroen79
author_rank: Frequent Contributor
timestamp: January 24, 2016, 09:36:51 am
content: The 12V one lists a max current of 350 mA.The 5V one is specified with a 42 ohm DC resistance.But if the specs don't tell you the current rating then you could always contact the seller and ask for more details.Or see if you can find the part's name and try to find a datasheet elsewhere.As a last resort you could buy the motors and test them.Make it turn with a resistor in series and then measure the voltage drop over that resistor. Be sure to test it with different loads.

author: Simon
author_rank: Unknown
timestamp: January 24, 2016, 09:57:51 pm
content: One way of playing it safe could be to measure a coil resistance in the motor assist would give you the start-up current expected. It's a bit rough and ready but at least you won't under design.
120V SSR - How to calculate resistors? - Page 1
Forum section: electronics / beginners

author: smssk
author_rank: Newbie
timestamp: January 20, 2024, 12:07:27 am
content: How do I go about calculating the required resistance to drop 120v AC down to 1.4v DC to drive the SSR at approximately 15ma in the attached circuit?

author: Halcyon
author_rank: Unknown
timestamp: January 20, 2024, 05:22:37 am
content: Duplicate thread.
120vac LEDs Six in parallel - One Flickers - Page 1
Forum section: electronics / beginners

author: NY2KW
author_rank: Regular Contributor
timestamp: January 31, 2020, 04:25:07 am
content: 2 years ago I bought some very attractive, pricey, recessed stairwell LED lights. They are each wired 120vac in parallel and controlled by a regular wall switch. One of the lights now flickers rapidly when turned on and I have to flip the wall switch numerous times until it finally stays lit. I have monitored line voltage and it is pretty constant between 119-122vac. I cannot get a replacement fixture... is the LED assembly something potentially repairable?jerry

author: Jwillis
author_rank: Super Contributor
timestamp: January 31, 2020, 06:17:31 am
content: Could be the driver circuit is getting ready to pack it in on that one or it could very well be a poor connection at that one.I would check the connections are solid and go from there.Can you get a couple photos inside the light fixture and if you can any circuit board.
121GW as phase/neutral indicator - Page 1
Forum section: electronics / beginners

author: strawberry
author_rank: Super Contributor
timestamp: August 27, 2023, 06:24:55 am
content: AC volts range internal 10Mshunt resistor is less than ~100M neon indicator but same ~1kV breakdown specnegative led connected to ground or hand and positive test lead to somewhere

author: Gyro
author_rank: Super Contributor
timestamp: August 27, 2023, 11:46:29 am
content: Holding the negative lead in your hand while probing the mains with the other would be an incredibly dangerous thing to do. The meter contains a VDR (voltage dependent resistor) to shunt high voltage transients and protect the meter. If you are holding the meter at the time of such a transient, it will go straight through you. You might also accidentally have the probe plugged into a current range jack!Holding the negative lead (actually it doesn't matter which way round as mains is AC) to ground, as long as you aresureit is ground rather, than Neutral is better. If you have a faulty ground though, you will get a false reading. The correct method to test for dead is Live-Neutral, Live-Earth, Neutral-Earth.If you are doing much of this sort of thing, then electricians' 2 pole testers are available for little money. These have decent CAT ratings, always work (no danger of wrong socket or dial setting) and even work with a flat battery (the ones with a continuity function too). Avoid handheld non contact 'death sticks' or meter NCV functions, their indications are not reliable enough to trust your life to! Handy for 'exploring' but nothing more.P.S. Neon screwdriver testers are not considered safe these days either.

author: strawberry
author_rank: Super Contributor
timestamp: August 28, 2023, 05:27:20 pm
content: I have admiral rank in engineeringMOV typically will subtract rated voltagespark gap and underrated components will short circuit and bypass full power

author: Gyro
author_rank: Super Contributor
timestamp: August 28, 2023, 07:09:25 pm
content: Quote from: strawberry on August 28, 2023, 05:27:20 pmA strange question to ask then. Actually, trying to read your OP again, is it a question? It doesn't seem to make sense.

author: Vovk_Z
author_rank: Super Contributor
timestamp: August 29, 2023, 08:06:26 am
content: Quote from: Gyro on August 28, 2023, 07:09:25 pmIt is not a question. We are use to have questions here, but occasionally somebody just shares it's experience.BTW, I use a multimeter as a phase indicator often too (though I have neon indicator of cause but if often is lying somewhere else). Typically I don't have to touch ground, so it is mostly quite safe. Sometimes when floor and walls are fully isolated material it shows nothing. But mostly it shows at least 10-20 VAC at phase (and zero at neutral or PE).
121GW Meter - Page 1
Forum section: electronics / beginners

author: Rob T
author_rank: Newbie
timestamp: October 21, 2018, 06:43:42 pm
content: Has anyone from Canada ordered this meter I was wondering how much it ended up costing

author: GeoffreyF
author_rank: Regular Contributor
timestamp: October 21, 2018, 08:03:26 pm
content: 279.37 at today's exchange rate. Shipping charges also apply. You can calculate yourself here.https://www.google.com/search?q=australian+to+canadian+dollars&rlz=1C1CHBF_enUS721US721&oq=australian+to+canadian+dollars&aqs=chrome..69i57.5254j0j7&sourceid=chrome&ie=UTF-8It is well worth it for the feature set provided.

author: bc888
author_rank: Regular Contributor
timestamp: October 22, 2018, 02:51:15 pm
content: It seems like the GW121 issues and problems thread has so much complaining that it's clear the meter is not ready for release yet. Is that not true? Meter is working fine?Need to add the link:https://www.eevblog.com/forum/testgear/eevblog-121gw-multimeter-issues/850/

author: GeoffreyF
author_rank: Regular Contributor
timestamp: October 23, 2018, 02:24:43 am
content: Quote from: bc888 on October 22, 2018, 02:51:15 pmNo it's not true. Much of that thread is regarding beta shipments, not released. I own one and it is really great for the money. It is stable and works great. There are meters more than twice the price with similar functions. Those more expensive settle on a value faster or handle multi-phase motors, capability valuable for someone who is solving problems in the field.The 121GW is out of stock. When it becomes available, it gets sold out in a day or so.

author: NexusKoolaid
author_rank: Contributor
timestamp: October 23, 2018, 04:30:26 am
content: You can also order this meter from Welectron (in Germany). Welectron is out of stock as well at the moment, but it looks like more are expected on the 26th of this month. He's fast - I ordered a Brymen 867s on a Friday evening (US), it was at my door the following Tuesday. You don't have to pay the VAT when ordering from North America, but the only shipment options offered are DHL and UPS.https://www.welectron.com/EEVBlog-121GW-Data-Logging-Multimeter-with-Bluetooth
121GW Multimeter - Bluetooth Logging Sample rate  - Page 1
Forum section: electronics / beginners

author: Ted123
author_rank: Newbie
timestamp: September 01, 2024, 09:36:20 am
content: Hi allI've just recently got the 121 GW multimeter, pretty happy so far.I did a uA test for the flame rectification check on a flame rod on gas heater, seemed to work well and was getting around 3 uA which sounds about right.I tried to do a cranking test on my car battery with the Bluetooth logging to see what the minimum cranking voltage it got. It seems to be around 10.3 volts as per the photos. 12.6 standing voltage, 10.3 cranking, 14.1 charging as per the photo. What is the sampling rate of the Bluetooth logging (how often does it take a reading) I had it on the ln0 setting and would this be a reliable test ?I have to say the set up and connecting of the app and Bluetooth for a novice and non EE like me.I tried to do the min and max reading but it kept saying 0 volt so I must have been doing wrong

author: J-R
author_rank: Super Contributor
timestamp: September 01, 2024, 09:33:09 pm
content: A typical DMM and this logging method in particular are going to be a bit slow for capturing a lot of detail. I'm not sure what you're trying to see, but you could pull your fuel pump fuse or otherwise prevent the car from starting to extend the cranking time.Another method: if you have an oscilloscope or DMM with a scope function, you could gather multiple seconds on the screen at great detail. For better accuracy, a bench DMM with a fast logging rate could also do this.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: September 02, 2024, 01:27:26 pm
content: Good Morning Ted123, Page 58 of the Users Manual explains how to use the Min/Max function. Also, logging voltage using the internal Micro SD card can allow youto take samples many times per second, or 1 per second by default. Page 54 of the manual will explain how to log data by just pushing the 'Mem' button. So, if you RTFM, all your questions will be answered. And welcome to the 121GW Club
121GW oddity - Page 1
Forum section: electronics / beginners

author: bashie
author_rank: Newbie
timestamp: August 31, 2023, 01:10:12 am
content: I recently got my 121GW and while tinkering today I noticed something interesting:When I tried to measure an 220K SMD resistor (marked 224), the meter read 149.xxK. I tried multiple times, and if the 121GW was in the 500K range it would read ~150kOhms, but it read 0.219 MOhms correctly if set to the 5M range.My UNI-T meter read the resistance correctly in both the 600K and the 6M range.

author: bashie
author_rank: Newbie
timestamp: August 31, 2023, 01:15:24 am
content: I changed the batteries to 4 L91s yesterday. I drained them a bit to get the voltages lower, to ~1.63V, similar to the OCV of a fresh alkaline. The meter reported 6.4V.When I switched back to alkalines it now reads ~215k in the 500K rangeIt now reads 215k even with lithiums. What's going onUpdate: with a fresh pack of L91s it reads 150k on a 224 and 216k on another 224. Why though

author: bashie
author_rank: Newbie
timestamp: August 31, 2023, 01:21:10 am
content: from the manual:> Lithium batteries have a higher voltage and may cause the device to malfunction.Are there any detailed explanations about this?

author: bashie
author_rank: Newbie
timestamp: August 31, 2023, 01:24:25 am
content: It now reads ~149.7 and ~219 in 500k and 5m ranges respectively with 4 fresh alkalines@Dave ?

author: EEVblog
author_rank: Unknown
timestamp: August 31, 2023, 07:24:50 am
content: The extra voltage from lithiums will not cause an accuracy problem. That's a red herring.Sorry, I know it's basic but I have to ask, you aren't touching the probes with your fingers are you?This fault is very odd.

author: bashie
author_rank: Newbie
timestamp: August 31, 2023, 08:33:02 am
content: No, definitely not. When I keep the probes in place (not touching) when it shows 150K, I can switch into the 5M range and it will show ~220K. Weird

author: Chalcogenide
author_rank: Regular Contributor
timestamp: August 31, 2023, 08:42:33 am
content: You are not measuring the resistance value while in circuit, right?

author: armandine2
author_rank: Frequent Contributor
timestamp: August 31, 2023, 09:01:14 am
content: Try regular THT resistors, first thing I'd have done after the weird SMD readings .

author: EEVblog
author_rank: Unknown
timestamp: August 31, 2023, 10:17:39 am
content: Quote from: Chalcogenide on August 31, 2023, 08:42:33 amThat was my next question.
12AC to 12vdc - Page 1
Forum section: electronics / beginners

author: CharlesTT
author_rank: Newbie
timestamp: January 25, 2020, 04:31:11 pm
content: Hi guys I am having a bit of a problem trying to get an led light to work. It is a 240v led light that I have replaced the driver with a 12v model that outputs 6v for the leds. The Waterproof transformer I am using ( it is fit an outside light ) outputs in AC and i'd rather not replace it as it is driving all of the other lights just fine.Is there a way I can convert its output to DC? Would I have to use a bridge rectifier and if so could you suggest one? or an alternative driver..CheersCharles

author: WattsThat
author_rank: Frequent Contributor
timestamp: January 26, 2020, 01:39:02 am
content: A 12 volt ac transformer will result in approximately 17 volts dc when rectified and filtered. A full wave bridge and appropriately sized capacitor followed by a switching buck regulator module is one way to achieve your goal. But, by the time you’re done with sourcing, fitting and mounting the additional parts required, it’s probably easier to purchase a dc output wall wort to power the led’s.Do you know what current at 12vdc is required for the led’s? Can they be driven with a constant voltage? An led driver is usually a constant current device.That’s the missing information at present for a more informed answer.

author: Zero999
author_rank: Super Contributor
timestamp: January 26, 2020, 03:06:04 pm
content: What sort of LEDs are they?The easiest way is to replace the LED or driver with one which is designed for 12VAC.
12v 5A ish step-up regulator - Page 1
Forum section: electronics / beginners

author: TheBekker
author_rank: Newbie
timestamp: September 24, 2016, 12:51:13 am
content: HiI'm working on a hobby project and its powered by a 7,4v lipo, but for some motors i need 12v.So im looking to make a simple boost converter, but cant really find a appropriate regulator for it.Can anyone recommend a regulator that can boost my 7,4v to 12v at 4-5A.Tried googling for some, and looked at the LM1084IT-12, but not sure if that actually can step up? or if its only down?Thanks in advance

author: Marco
author_rank: Super Contributor
timestamp: September 24, 2016, 02:17:43 am
content: Literally hundreds of external switch converter ICs which can do that. Just search for boost on digikey and select the switching controllers category.Or buya module.

author: Audioguru
author_rank: Super Contributor
timestamp: September 24, 2016, 02:27:07 am
content: The 2-cells Li-Po battery voltage will drop to 6.4V as it discharges, then if the efficiency of the boost circuit is 80% and it must produce 12V at 5A (60W) then the battery must produce 75W which at 6.4V is a current of 75W/6.4V= 11.72A. Can the Li-Po produce such a high current continuously without catching on fire?

author: Towz
author_rank: Contributor
timestamp: September 24, 2016, 02:35:37 am
content: The LM1084 is a linear low dropout regulator, this it need a supply higher than the desired output. You need a boost (or flyback) converter like the LM2585-12 or similar, you might even whip out your own converter with a low end micro or even just opamps. Lots of ways to do it.