hybridfree/eevblog-posts huggingface dataset:
Controlling one microcontroller with a second microcontroller - Page 1
Forum section: electronics / beginners

author: Dave Wave
author_rank: Contributor
timestamp: June 30, 2018, 03:21:47 am
content: I am working on a project with an ESP8266 microcontroller. One of the digital pins is held high with a pull up to 3.3v. When a switch is closed, the line goes to ground, it triggers an interrupt in the ESP8266, which then logs the event.This part works fine.What I want to do is to get rid of the switch and ground, and drive the line low with at Attiny85.With a pull-up resistor and 3.3V source tied to the pin on the ESP8266, can I connect that line one of the digital pins on the Attiny85, and use that to pull the line low (digitalWrite(Pin, LOW))?Both chips are powered from the same power supply.Will this work? Do I need to change the value of the pull up resistor (220 ohm )?Thanks-Dave

author: a59d1
author_rank: Regular Contributor
timestamp: June 30, 2018, 03:29:54 am
content: The pull-up value doesn't really matter - a dead short would be fine instead if you never needed to pull the line low - but most people go for a larger value around 1K to reduce the current wasted when the pulled-up line is pulled down by a uC. No need to burn 15mA just for an interrupt signal!

author: bson
author_rank: Unknown
timestamp: June 30, 2018, 02:03:49 pm
content: You don't strictly need a pullup at all if you connect it to a GPIO output. Keep the output high and momentarily strobe it low to log an event. When used like this you want a pullup mainly so the signal has a known state during power up or if the controlling CPU resets. In this case you want aweakpullup, with around 10k-47k being typical.

author: rstofer
author_rank: Super Contributor
timestamp: June 30, 2018, 07:56:24 pm
content: I prefer to add a 330 Ohm resistor to all IO pins but I would just use one where the signal is pin-to-pin. The value is low enough that it doesn't alter timing but it does prevent a short circuit - like when both pins are configured as outputs and set to opposing logic levels.
Controlling speed of EDF motor - Page 1
Forum section: electronics / beginners

author: Theboel
author_rank: Frequent Contributor
timestamp: December 08, 2020, 10:28:43 am
content: HiI am looking for advice on how to control the speed of EDF motor without using the remote control, I need to control the speed based on pressure. (0,4 bar)any help will apreciate.https://www.turbines-rc.com/en/jp-hobby/1062-edf-ducted-fan-jp-hobby-90mm-12s-motor.htmlthis is my target motor.Thank YouAnton

author: Berni
author_rank: Super Contributor
timestamp: December 08, 2020, 10:34:09 am
content: Hook up a I2C pressure sensor IC to a microcontroller then have the microcontroller generate the PWM servo signal to drive the throttle of the motor controller.

author: Theboel
author_rank: Frequent Contributor
timestamp: December 08, 2020, 02:40:27 pm
content: Hi Berni,Thank you for suggestion I start looking for an Arduino project.Regards,Anton

author: Benta
author_rank: Super Contributor
timestamp: December 08, 2020, 06:25:13 pm
content: Quote from: Berni on December 08, 2020, 10:34:09 am+1Buy the recommended BLDC motor controller as shown on the web page, and generate a 1...2 ms PWM pulse with 20 ms repetition rate from your microcontroller.Getting the PID loop right is probably going to be the most difficult part.

author: firehopper
author_rank: Frequent Contributor
timestamp: December 08, 2020, 11:48:29 pm
content: and to clarify things. 1ms is low throttle or off. 2ms pulse is full throttle or fully on. and please keep fingers out of the spinning blades of death while on
Conversion Formula  - Page 1
Forum section: electronics / beginners

author: Bill8989
author_rank: Newbie
timestamp: December 01, 2019, 08:16:37 pm
content: Hi, I was wondering if anyone could tell me how I could work out the energy losses from the AC-DC step down when I plug my 5v phone charger into a 230v RMS AC mains supply? given that my phone is probably drawing around 1A and this should give a 5W load on the supply.

author: ArthurDent
author_rank: Super Contributor
timestamp: December 01, 2019, 08:36:34 pm
content: Most chargers are switching mode power supplies (SMPS) and have a conversion efficiency of 80%-90% plus as your phone approaches full charge, the current it draws will drop quite low. I would guess that the load on the mains initially would be a maximum of about 6 watts and drop to a very low value as the phone is charged.I use a Kill-A-Watt monitor which is fairly cheap and could gives me information on the mains side. Just make sure to get the UK version.https://www.amazon.co.uk/Energenie-429-856UK-Power-Meter/dp/B003ELLGDC
Conversion from positive pulse to negative pulse - Page 1
Forum section: electronics / beginners

author: dk-001
author_rank: Newbie
timestamp: June 28, 2020, 04:49:06 am
content: Hi,For a low current power supply project I need positive and negative square pulses around 200 kHz frequency. Another requirement for the square wave is to have a variable amplitude between 0-10V. Some 555 timers can provide amplitudes close to Vin, so I can vary the Vin for 555 chip and get a variable amplitude. Could you please recommend a method to convert positive pulse to negative pulse (i.e. -10V to 0V) from these or maybe another method?I'm planning to use these as input to Cockcroft-Walton multiplier. If possible I would like to avoid using a transformer, and generate voltage (0V-100V or -100V - 0V) on the board by using 5V pr 9V DC input, without a need for negative power rail.Thank you.

author: greenpossum
author_rank: Frequent Contributor
timestamp: June 28, 2020, 04:55:36 am
content: Quote from: dk-001 on June 28, 2020, 04:49:06 amBy Vin do you mean the supply voltage to the 555? You'll find that the 555 will not function below a certain supply voltage, certainly not 0.

author: dk-001
author_rank: Newbie
timestamp: June 28, 2020, 05:34:29 am
content: Yes, I meant Vin to 555. I see you point. I don't need to go down to 0V as output if I cannot accomplish the requirements (i.e. I can live with a certain startup value).

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 28, 2020, 07:10:41 am
content: Hi,You don't need a -10V pulse to get negative voltages from a Cockcroft-Walton multiplier.As the voltage goes up, the current goes down. You will only be able to get a few mA at 100V.Regards,Jay_Diddy_B

author: David Hess
author_rank: Super Contributor
timestamp: June 28, 2020, 03:23:38 pm
content: Like Jay_Diddy_B says, a Cockcroft-Walton multiplier can be AC coupled on its input so reversing the diodes will invert the output.
Conversion to TTL signal with transistor - Page 1
Forum section: electronics / beginners

author: ocayfs
author_rank: Newbie
timestamp: April 30, 2014, 02:19:32 pm
content: Hi,i want to use this circuit to convert the signal in the input to a TTL signal, but i don't now if the values of resistors are ok. If i understand, we should have a current IBthat ensures the saturation of the transistor. I calculated IBwith Thévenin transformation :Rth= R1 // R2 = 824 ohmEth= Vcc*R2/(R1+R2) = 0.877 VIB= (Eth- VBE)/Rth= 0.21 mA (VBE= 0.7 V)Another question : what is the beta of this transistor (PN2222A) ? should i measure it ?

author: tszaboo
author_rank: Super Contributor
timestamp: April 30, 2014, 02:26:09 pm
content: TTIUWPhttp://www.urbandictionary.com/define.php?term=TTIUWP

author: ocayfs
author_rank: Newbie
timestamp: April 30, 2014, 02:56:57 pm
content: Oh sorry i forgot the picture

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 30, 2014, 08:45:04 pm
content: Impossible to say if it will succeed, without knowing what the input signal is.The transistor itself, if driven into saturation or cutoff, will deliver a more-or-less TTL-compatible signal.Tim

author: KJDS
author_rank: Super Contributor
timestamp: May 01, 2014, 09:19:53 am
content: I predict oscillations, and what is the input capacitor for?

author: David Hess
author_rank: Super Contributor
timestamp: May 02, 2014, 12:26:37 am
content: Quote from: KJDS on May 01, 2014, 09:19:53 amThe input signal is AC coupled to remove a DC component or level shift it. That is not unusual.

author: ocayfs
author_rank: Newbie
timestamp: May 02, 2014, 11:42:52 am
content: KJDS what do you mean by oscillations ?

author: ocayfs
author_rank: Newbie
timestamp: May 08, 2014, 09:09:54 pm
content: Can someone help me please, it is for a frequency counter with PIC. The input signal can be sine, square or triangular.

author: KJDS
author_rank: Super Contributor
timestamp: May 08, 2014, 09:18:07 pm
content: Quote from: ocayfs on May 02, 2014, 11:42:52 amAny transistor with two of it's pins without any series resistance will always have a layout dependent risk of oscillation.

author: miguelvp
author_rank: Super Contributor
timestamp: May 09, 2014, 01:38:18 am
content: http://www.adafruit.com/products/757not the hardware but look at the technical details for the Phillips app note for an bidirectional I2C level shifter, there is a newer app note with the newer Phillips name in there as well.Would that do what you want?Btw, it's intended for up to 400Kbits/s

author: miguelvp
author_rank: Super Contributor
timestamp: May 10, 2014, 08:05:17 pm
content: If you need something faster and it's unidirectional this transceiver will deal with 8 inputs up to 500Mbpshttp://www.wvshare.com/product/74LVC8T245-Board.htm
Convert -10V to +15V, into 0-5V - Page 1
Forum section: electronics / beginners

author: AQUAMAN
author_rank: Regular Contributor
timestamp: July 08, 2014, 02:36:33 pm
content: Hello all, this thread is related to another thread I posted and got great help with.I have a gate driver and I want the gate voltage to control a CMOS switch that is 0-5VThe problem is that I can't access the 'gate trigger signal' from the gate driver (ie the 0-3.3/5V signal I get from the DSP), so Im stuck with looking at the full -10V - +15V gate voltage.Is there a way to convert this signal to 0-5V? I thought of a voltage divider and a diode, as I dont need much current to control these switches (http://www.analog.com/static/imported-files/data_sheets/ADG719.pdf)But even here I can only get -0.6V to 5V and Im not sure the switch will take that negative voltage as in the data sheet it says that it can take -0.3V at a maxOtherwise, I have to include another optical fibre terminal and additional pulse from my DSP. Actually the board I built has this but I would like very much to save space.

author: jmoreland79
author_rank: Regular Contributor
timestamp: July 08, 2014, 03:06:11 pm
content: Why not just use a positive voltage regulator to handle the -10V to +15V? Datasheet attached.
Convert 12V DC to 9V DC ? - Page 1
Forum section: electronics / beginners

author: Nhan95
author_rank: Contributor
timestamp: April 15, 2015, 03:53:35 pm
content: Hi. I have an adapter 12V. And I want to convert to to 9V DC. Is there any circuit to do that ?

author: mariush
author_rank: Super Contributor
timestamp: April 15, 2015, 03:57:44 pm
content: A simple linear regulator 7809 and a couple of capacitors will do that for you. Search for "7809" at any electronics online store, you'll find lots of companies making chips with this 7809 in the name.See page 18 for example circuit :https://www.fairchildsemi.com/datasheets/LM/LM7809.pdfIf you want better efficiency, there are lots of switching regulator chips you can look at, and the datasheets for them typically have example circuits you can adapt to output 9v from them. All you have to do is read.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 15, 2015, 04:21:10 pm
content: Quote from: Nhan95 on April 15, 2015, 03:53:35 pmMany. Depends on what the 12V looks like and what current you expect to draw at the 9V end. A simple resistor can do the job too if you know what you're doing.

author: Simon
author_rank: Unknown
timestamp: April 15, 2015, 04:39:49 pm
content: The way the question is posed sounds like it's generic and must supply any current.

author: Simon
author_rank: Unknown
timestamp: April 16, 2015, 11:11:56 am
content: Quote from: aidan2496 on April 16, 2015, 11:07:31 amJudging from your last question that I just answered...... NOwhat do you actually intend doing ?

author: GoneTomorrow
author_rank: Regular Contributor
timestamp: April 16, 2015, 12:58:08 pm
content: Quote from: aidan2496 on April 16, 2015, 11:07:31 amOnly when the current is known and stays essentially exactly the same (voltage drop across a resistor is the product of current and resistance; if current goes up, voltage drop goes up). It's also the least efficient method, as all power (Vdrop x current) is dissipated as heat.A linear regulator at least gives you feedback so you can handle varying currents easily, but they have the same dissipation issue as plain resistors. Most standard linear regulators are good for up to about 1 amp, though only with a heatsink as in this case you would be dissipating 3W.For higher currents you'd want to go with a switch mode supply, as these avoid most of the heat issues of linear regulators and resistors.
Convert 1GB BASE KX to 1 GB BASE T - Page 1
Forum section: electronics / beginners

author: chinoPR
author_rank: Newbie
timestamp: March 03, 2025, 11:59:07 pm
content: Hi everyone! I'm trying to design a backplane with a 1GB-BASE KX interface, which is output as 1GB BASE-T. Unfortunately, to my surprise, I couldn't find a specific PHY for this conversion. Does anyone have experience with this type of interface? Thanks a lot.
Convert cheap (Mastech) power supply to constant current dummy load - Page 1
Forum section: electronics / beginners

author: kc9qvl
author_rank: Regular Contributor
timestamp: March 30, 2014, 04:55:08 pm
content: Had another pass transistor fail in my hy1803d. Since getting this supply have upgraded to other better supplies. So instead of repairing I'm thinking it might make a nice constant current load. Use Dave's circuit mostly but reuse the current shunt. It measures 100mv per amp low side. If i add 10x gain to the second opamp it should operate correctly.Will this work? Bad idea?

author: madires
author_rank: Super Contributor
timestamp: March 30, 2014, 05:25:17 pm
content: Is the pass transistor a 2N3055? Assuming that the transformer tap is switched around 10V the maximum power dissipation is going to be around 10V * 3A = 30W. A 2N3055 on a proper heatsink should be able to handle that without any problem (max. 115W).Before starting to design a constant current load please determine the specs, like max. current and voltage. If you are going to use the original heatsink you're limited to 30W.

author: kc9qvl
author_rank: Regular Contributor
timestamp: March 30, 2014, 06:40:47 pm
content: Going to replace 2n3055 (bad anyways) with a fet.Heat sink should do 54 watts 18v x 3 ampsThis what I have in mind:

author: madires
author_rank: Super Contributor
timestamp: March 30, 2014, 09:34:30 pm
content: Are you sure about the heatsink? AFAIK the Mastech PSUs use a transformer with multiple taps to reduce the power dissipation. A quick search for the HY1803 shows two taps in series switched by a relay. Your circuit seems be ok. I'd go for a more recent OPamp. If you don't got a stable Vcc you could use a TL431 as voltage reference. And check for any oscillation. Maybe you have to add some small value caps.

author: kc9qvl
author_rank: Regular Contributor
timestamp: March 30, 2014, 11:56:50 pm
content: Pretty sure about the heatsink. Its a 18 volt at 3 amps . The Highest tap on the transformer is 26 volts and is switched in at 9 v dc. Heatsink should be fine to 50 watts. If not have a taller one with similar profile.Got a bit done. Decided that the low ohm shunt was just a pain so bodged in a resistor. 1 ohm is now one amp.Started on the board. Using 2) 2 ohm 25 watts for the shunt resistor. 8 volt regulator what i had. The other transformer is to power the panel meters

author: kc9qvl
author_rank: Regular Contributor
timestamp: March 31, 2014, 03:01:44 am
content: Got rest of power supplies together. Added 12 volt regulator for fans. More to followDid some math on the heatsink has a thermal resistance of about 4 c/watt. might not workWill just have to see.
:: convert ORCAD spice to PSPICE? - Page 1
Forum section: electronics / beginners

author: 3roomlab
author_rank: Frequent Contributor
timestamp: April 25, 2014, 03:29:46 pm
content: is there a way to convert this infineon MOSFET orcad spice to PSPICE/LTspice?.SUBCKT IPP039N04L_L1 drain gate source PARAMS: dVth=0 dRdson=0 dgfs=0 dC=0 Ls=2n Ld=2.5n Lg=4n.PARAM Rs=941u Rg=1.6 Rd=350u Rm=244u.PARAM Inn=80 Unn=10 Rmax=4.2m gmin=76.PARAM act=4.466X1 d1 g s Tj S4_40_h_var1 PARAMS: a={act} dVth={dVth} dR={dRdson} dgfs={dgfs} Inn={Inn} Unn={Unn}+Rmax={Rmax} gmin={gmin} Rs={Rs} Rp={Rd} dC={dC} Rm={Rm}Rg g1 g {Rg}Lg gate g1 {Lg*if(dgfs==99,0,1)}Gs s1 s VALUE={V(s1,s)/(Rs*(1+(limit(V(Tj),-200,999)-25)*4m)-Rm)}Rsa s1 s 1MegLs source s1 {Ls*if(dgfs==99,0,1)}Rda d1 d2 {Rd}Ld drain d2 {Ld*if(dgfs==99,0,1)}E1 Tj w VALUE={TEMP}R1 w 0 1u.ENDSas it is, the model seems not to respond to gate voltage. what should be editted? does anyone have any idea?

author: 3roomlab
author_rank: Frequent Contributor
timestamp: April 26, 2014, 02:14:41 am
content: anybody knows anybody at fairchild semi? lol

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 26, 2014, 02:56:32 am
content: Doesn't OrCAD already use PSpice..?!Only thing dubious I see is the G statement, which should beCode:Bname n1 n2 I={expression}But it's hard to say without also the S4_40_h_var1 subckt.Tim

author: 3roomlab
author_rank: Frequent Contributor
timestamp: April 26, 2014, 06:17:36 am
content: well, my brains are not working now ... but i have been comparing this to other MOSFET files and ... this looks so weird.im not familiar with SPICE statements so im lost when you say G ...i am assuming LTspice pdf have a full run down of what every symbol means?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 26, 2014, 08:17:20 am
content: http://www.seas.upenn.edu/~jan/spice/spice.overview.html
Convert plug in speakers to bluetooth wireless - Page 1
Forum section: electronics / beginners

author: dleebell
author_rank: Contributor
timestamp: April 30, 2021, 02:31:34 pm
content: Hello everyone!I'm wanting to convert my current USB ''plug in'' Logitech speakers into bluetooth wireless speakers. The 1st goal for this is to be wireless and to reduce/eliminate any open wiring.This is what I have already to quickly trial the set up before soldering anything, see attached picture:- USB powered speakers (Logitec Stereo Speakers Z120)- 2pcs Bluetooth Audio Receiver Board for Audio Amplifier MP3 Lossless Decoder 3.7-5V BT5.0- 10400mAh Power Bank Quick Charge 3.0, Mini USB C Power bank Portable Charger USB C Battery Pack 18W Power Delivery Fast Charge compatible with iPhoneNow the speakers and bluetooth receiver can be turned on with this battery bank and play music for a few seconds before the battery goes into some form of standby mode, possibly as a safety precaution from too much current?My understanding is that in order for this to work I need a 5V 2A Battery bank? If this is the case does anyone know of a good place to buy a battery pack that is fairly compact with this spec? Ideally something that can fit in a 10cm x 9cm area.Much appreciated from any help

author: jonovid
author_rank: Super Contributor
timestamp: April 30, 2021, 03:00:30 pm
content: why reinvent the wheel, wireless speakers arecheapas Chinese chips.if u know one end of a soldering iron from the other end & what a DMM is thenits easy as.swap out the best speaker drivers and enclosures with the wireless speaker pcb unit of your choosing.

author: oPossum
author_rank: Super Contributor
timestamp: April 30, 2021, 03:19:30 pm
content: Quote from: dleebell on April 30, 2021, 02:31:34 pmMore likely too little current rather than too much.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 30, 2021, 04:10:45 pm
content: Quote from: oPossum on April 30, 2021, 03:19:30 pmIndeed. Li-Ion does not output 5V, but a power bank usually does, and keeping an SMPS circuit running when it's not needed drains the battery. Therefore some of the "power bank chips" turn off the output when the load is too light. This is pretty annoying if you want to use it for light loads, so you have to find a circuit that is fit for this purpose.
Convert ppm/sqrt(kHr) to ppm/1000hr - Page 1
Forum section: electronics / beginners

author: michaeliv
author_rank: Frequent Contributor
timestamp: January 26, 2016, 09:42:24 am
content: Hello,Looking at the datasheet for the LTC6655 voltage reference, it's long term drift is specified as "60 ppm/sqrt(kHr)" - parts per million per square root kilo hertz.I've tried searching around but I can't seem to find a way to convert this to ppm per 1000 hours. Can anyone link to more information - what does the unit actually mean ?LTC6655 voltage reference datasheet:http://cds.linear.com/docs/en/datasheet/6655fe.pdfThanks!

author: Brumby
author_rank: Unknown
timestamp: January 26, 2016, 10:19:22 am
content: Hr is not Hz

author: Chalcogenide
author_rank: Regular Contributor
timestamp: January 26, 2016, 10:20:58 am
content: 1 kHr = 1 kilo hour = 1000 hours.

author: michaeliv
author_rank: Frequent Contributor
timestamp: January 26, 2016, 05:33:21 pm
content: Quote from: Brumby on January 26, 2016, 10:19:22 amQuote from: Chalcogenide on January 26, 2016, 10:20:58 amOulps ... I honestly read it Hz until you pointed that out. I guess it's one of those cases where your mind "auto-corrects" what it think is misspelled.But why the square root ? Does it mean 20ppm / 31.6hr ?

author: Ian.M
author_rank: Super Contributor
timestamp: January 26, 2016, 05:40:05 pm
content: It means the drift slows down with time. You cant convert it to a linear drift with time as they have different physical units, t-1/2and t-1

author: michaeliv
author_rank: Frequent Contributor
timestamp: January 26, 2016, 05:51:26 pm
content: Quote from: Ian.M on January 26, 2016, 05:40:05 pmThat makes sense, so how would I calculate the total drift in the first 1000hr ?

author: tszaboo
author_rank: Super Contributor
timestamp: January 26, 2016, 05:55:02 pm
content: Yes it does. For the first 1000 hours it is maximum 60ppm. For the first 4000 it is 120 and 180 for 9000 hours. Pretty simple. If you threat your reference well, the value might be much less, if you mistreat it, it will be worse.

author: awallin
author_rank: Frequent Contributor
timestamp: January 27, 2016, 06:12:54 am
content: I guess that spec means the voltage follows a random walk and could be anywhere within the +/- XX/sqrt(time) parabolic region.Here's an image (unrelated to voltage references, just simulated random walk)http://blog.oraylis.de/wp-content/uploads/2015/10/Rplot02_thumb.pngA really nice manufacturer or lab might buy 100 references and measure them all and put that in the datasheet - maybe there are example images out there?
Convert S-Parameters from 2 ports to 4 ports - Page 1
Forum section: electronics / beginners

author: RFbeginner
author_rank: Newbie
timestamp: September 01, 2019, 07:44:15 pm
content: Hello everyone,I am currently working on de-embedding coplanar stripline designs. I have boards with one input and one output constituted of Hybrid-CPS design-Hybrid and I have measured SP of the hybrids. I first tried to convert the SP of the hybrids from 4 ports to differential 2 ports but it messes up the impedance and the deembedding doesn't work, so now I'm trying the opposite, which is to convert the S2P of the boards into S4P, deembed them and then convert them back to S2P and see the results. but i can't figure how to efficiently convert the S2P files to S4P files...Does any of you can give me a tip on how to do that ? or a matlab function perhaps ?Thanks.
Convert 12VDC to 300VDC - Page 1
Forum section: electronics / beginners

author: ChiefHumble
author_rank: Newbie
timestamp: January 26, 2012, 05:42:29 pm
content: Hi!I have some 300V capacitors that i need to charge up for my coilgun project. I've used a board from a disposable camera to charge the capacitors, but it doesn't quite give the kick... The capacitor bank is on 10mF, and you could imagine how long it takes to charge them up to 300V.Since it's a coilgun i want the charger to be a bit mobile, that's why it would be nice to convert the voltage from a 12V power supply (like a 12V battery).(The capacitors are rated to 330V)Any ideas?

author: firewalker
author_rank: Super Contributor
timestamp: January 26, 2012, 05:50:33 pm
content: Use a UPS. Rectify the output and charge the caps.Alexander.

author: IanB
author_rank: Super Contributor
timestamp: January 26, 2012, 06:31:07 pm
content: Quote from: ChiefHumble on January 26, 2012, 05:42:29 pmDo you mean 10,000 uF?Let's see: 0.5 x 0.01 x 300^2 = 450 JI'll come to your funeral after you kill yourself.

author: ejeffrey
author_rank: Super Contributor
timestamp: January 26, 2012, 06:50:38 pm
content: I assume you don't need great regulation. A simple unregulated push-pull SMPS should work OK for this application. You can find a basic schematic about halfway down this page:http://www.radiolocman.com/shem/shem-cache.html?di=19174You will have to wind your own transformer, and do a bit of calculations to get things right, but it should work OK.

author: Noize
author_rank: Regular Contributor
timestamp: January 26, 2012, 07:09:27 pm
content: Quote from: IanB on January 26, 2012, 06:31:07 pmAnd give him a twenty one coil gun salute

author: siliconmix
author_rank: Frequent Contributor
timestamp: January 26, 2012, 08:15:26 pm
content: is it a single coil setup of mutiple ?
Converting a 5v usb battery to 3v3 - Page 1
Forum section: electronics / beginners

author: kolonelkadat
author_rank: Regular Contributor
timestamp: October 08, 2016, 08:17:34 pm
content: Is it possible to convert one of those cheapo 5v usb battery back ups to output 3v3 instead? I figured I could just change a cap or something but it looks like there are a couple of micros in the circuit that im afraid will override any changes to the analog portion of the circuit.eta: or is there a 3v3 battery/usb charging module commercially available that I could just buy?

author: Zero999
author_rank: Super Contributor
timestamp: October 08, 2016, 08:54:20 pm
content: The easiet option is to just add a 3.3V regulator on the output. If a long battery life is required then a buck converter would be best.

author: cowana
author_rank: Frequent Contributor
timestamp: October 08, 2016, 10:22:57 pm
content: The issue you'll have is most powerbanks have a single cell lipo (or paralleled lipos), giving somewhere between 3v (empty) and 4.2v (full). To get to 5v, they have a boost switch mode converter, increasing the voltage. Changing the voltage it outputs is usually as simple as twekaing a resistor value or two (within limits).However, for a 3.3V output, this requires a significant change in topology - you're no longer boosting the voltage at all times. If the battery is 4.2v, it needs to be reduced (with a buck converter) - and if the battery voltage is 3v, it does need boosting as before.Your simplest option is probably modifying the feedback resistors to reduce the boosted voltage to around 4.4v, then adding a linear 3.3v regulator on the output.
converting a huntron tracker - Page 1
Forum section: electronics / beginners

author: m3vuv
author_rank: Super Contributor
timestamp: April 27, 2022, 02:21:53 am
content: hi all i have a huntron tracker with a u/s mains transformer,most of the voltages i can find with an old transfo from a cro,except the crt eht,would it be possible to use a tft display with it?,just seems too good to bin and chances of geting a replacement transformer are just about zero!.

author: mikerj
author_rank: Super Contributor
timestamp: April 27, 2022, 09:42:38 am
content: Is the primary or secondary bad? If it's a conventional E type core with separate primary and secondary you could try unwinding the O/C winding, carefully counting turns until you find the fault and then either repair the break or re-wind with suitable enamel wire. It might even be a built in thermal fuse which are usually fairly accessible after removing some of the outer insulation. I've successfully repaired a couple of old scope transformers like this, time consuming but not that difficult.

author: CaptDon
author_rank: Super Contributor
timestamp: April 27, 2022, 01:44:42 pm
content: Why wouldn't an old CRO transformer have the EHT winding? all of the older EICO, HEATHKIT, HICKOK and so forth using tubes like the 5UP1 or 5DEP31 and such all had one transformer with filament, B+, CRT filament and CRT EHT windings. You could use a small 2.5Kohm to 8 ohm audio transformer driving the 8 ohm side with a mosfet and a narrow pulse width signal at about 1Khz and rectify (with fast diodes) the 2.5Kohm winding. Should give you about 1KV. Those old CRO transformers are big, never going to fit into a tracker. The D.C. supply to the audio transformer supply idea should be around 12vdc. basically you are creating a simple flyback circuit. The load on the secondary will limit the flyback spike on the mosfet to around 200vp but you need a really fast pull down on the mosfet gate to get as much inductive kick as possible.

author: m3vuv
author_rank: Super Contributor
timestamp: April 27, 2022, 11:38:35 pm
content: the primary got nicked with an angle grinder(long story),i have an old tek scope transfo but i need 300+volt for a voltage doubler,the acceleration voltage is speced at 1350v,i tried getting that but the most i could get was 600v,that was using a cockcroft walton multiplyer,thats what made me think of a tft pannel,guesse thats a vector type tho?,its something i dont know anything about tbh.
Converting a stereo amp to a mono amp - Page 1
Forum section: electronics / beginners

author: aldfrarug
author_rank: Newbie
timestamp: August 14, 2021, 12:26:08 pm
content: Hello there,just wanted to know if it would work, if I were to connect the stereo positive and negative terminals of an amp to each other (L_pos + R_pos and L_neg + R_neg) to connect a single speaker to a stereo amp output.And BTW I don't really have a chance to convert the signal to mono before it goes into the amp as I want to keep the stereo signal for another output which is actually stereo.Thanks in advance!

author: mc172
author_rank: Frequent Contributor
timestamp: August 14, 2021, 12:36:09 pm
content: Why not just connect the speaker to either the left or right output and leave the other not connected?

author: Benta
author_rank: Super Contributor
timestamp: August 14, 2021, 01:13:38 pm
content: Don't connect your outputs together, odds are you'll fry them.Just use one channel.

author: magic
author_rank: Super Contributor
timestamp: August 14, 2021, 01:24:37 pm
content: As above.Offset voltages of the two channels are not guaranteed equal, a DC voltage will likely exist between them.Gain is not exactly equal either due to resistor tolerance, so signals on one channel will be slightly larger than on the other.Effect: short circuit current from one channel to the other. Not good.And the elephant in the room: you talk about two different signal being averaged. That's really not a good idea.

author: gf
author_rank: Super Contributor
timestamp: August 14, 2021, 01:34:35 pm
content: What about feeding L+R into one input and -(L+R) into the other one1), and treating the two amps as bridge amplifier?Otput power is twice the power of a single amp then, but the single speaker needs to have twice the impedance.Also in this configuration, DC offset is a potential issue, unless the speaker were AC coupled.Edit: Are these fixed gain amplifiers, or does each of them have its own volume (and possibly tone) control? If yes, then this is an additional complication.1)This basically requires a summing pre-amp, and an inverter
Converting a variable pulse into a switched dc voltage - Page 1
Forum section: electronics / beginners

author: schembri_andrew
author_rank: Newbie
timestamp: September 15, 2014, 04:33:00 am
content: Hi!I have an rc receiver, and would like to use it to switch a dc motor (either on and off without the proportional speed contro.. Maybe extent to reverse with an h bridge later on). How could i go about converting the high and low pulse width from the reveiver to an on and off state? I read about controlling a servo and use it to push a microswitch at its extremity which in turn switches a relay but i would prefer a solid state switching method.I found rc switches for sale but where is the fun in that?

author: Rerouter
author_rank: Super Contributor
timestamp: September 15, 2014, 07:29:18 am
content: Average the pulse into DC with an RC filter, feed into a comparator and have it drive a switching element e.g. an NPN for turn on or off your motor, you exceed the threshold and its on, fall beneath it and its off,only consideration may be using a resistor to add some hysteresis so you have to decrease a bit before it turns back off to prevent any risk of oscillation

author: macboy
author_rank: Super Contributor
timestamp: September 15, 2014, 04:10:32 pm
content: One of the complications is that the classic R/C control system uses pulse width to specify the servo/throttle position, but says nothing of pulse rate. So you might be able to use a simple R-C filter to get a DC value and feed this to a comparator and tweak it until it works, but the moment that the pulse rate changes, it will stop working. You need a circuit where the pulse width is measured and the pulse rate won't matter. Pulse width of 1 ms is full one left, and 2 ms is full right, with 1.5 ms being centered. (left/right are relative).Did you Google?. Lots of information there.

author: David Hess
author_rank: Super Contributor
timestamp: September 17, 2014, 05:00:27 am
content: The old PWM radio control systems I have played with had constant off time with variable pulse widths so the on time for the other channels would affect the off time for any one channel.I would integrate the pulse width and reset the integrator during the off time. Then if the output from the integrator is high enough, trigger a retriggerable monostable multivibrator which activates the motor driver.
converting analog video signal to digital video signal - Page 1
Forum section: electronics / beginners

author: alattin
author_rank: Newbie
timestamp: March 20, 2014, 11:41:39 am
content: I have a small project I am trying to make. I am looking to convert analog video from an old security camera with a BNC output connector to a digital signal that can be displayed on a computer.I know I need to have a male BNC connected to a small device that converts the signal and then a USB to connect to the computer... the part in the middle is what I am having a hard time with.What kind of chip, or microprocessor, or device do I need to convert the signal? I would like to make this as small as possible.Thanks for any input.

author: kolbep
author_rank: Frequent Contributor
timestamp: March 20, 2014, 12:25:40 pm
content: If you get something like :http://www.ebay.com/itm/New-4-Channel-USB2-0-DVR-CCTV-Video-Audio-Capture-Adapter-Card-/181157978365?pt=US_Surveillance_Digital_Video_Recorders_Cards&hash=item2a2ddb60fdIt lets you connect up to 4 cameras to this unit, which plugs into your pc.You then install the software, and it acts like a cctv system

author: Shock
author_rank: Super Contributor
timestamp: March 20, 2014, 03:30:54 pm
content: Many old tv tuner cards and some video cards had composite video in (single channel video, no audio).
Converting dc to ac to inductivly power and object - Page 1
Forum section: electronics / beginners

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: April 16, 2014, 08:28:56 am
content: Hello,I have a small project that i am thinking of doing at the moment however one of the main factors which will effect if i can do it or not is how to get a Sine wave (poth positive and negative voltages) from a +- dc supply (maby split supply with virtual ground)How would i go about making a sinewave using a micro? I know i would have to use the pwm on it to drive some mosfets but how would i actualy inplement it?

author: Simon
author_rank: Unknown
timestamp: April 16, 2014, 08:39:37 am
content: you will need to keep changing your duty cycle value and then apply a suitable low pass filter on the output to extract the sine from the train of square pulses.

author: tszaboo
author_rank: Super Contributor
timestamp: April 16, 2014, 08:51:00 am
content: I'm not sure why you would ever need a microcontroller to do that. Just make an oscilaltor for the correct frequency. If you need high currents and stuff, connect it to this:http://www.ti.com/tool/TIPD108and route the output to a mosfet with a driver. Why would you complicate your life that much?I'm even sure that with one or two 555 you can generate a sine wave.

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: April 16, 2014, 09:12:01 am
content: I ran out of 555 timers a few days ago and i have a few atmegas running around at te moment so i was going to use them temporaraly untill i can get some more 555's

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: April 16, 2014, 09:13:22 am
content: Ok so am i going to need an n channel mosfet (while im using the atmega) so that i can drive the 12v rail and then a p chanel for the -12v rail?
Converting DC to AC?  - Page 1
Forum section: electronics / beginners

author: mattintc
author_rank: Newbie
timestamp: May 05, 2013, 02:39:16 am
content: I cannot wrap my brain around how to do so. I have tried building a chopper out of a relay and all i want is to go from 24VDC to 24VAC. The reason being is because i want to power some contactors and such and got some telephone transformers for free and would love to put them to use instead of having to buy a 24VAC transformer. Iv googled like crazy too! Anyone that can help id more than appreciate it.

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 05, 2013, 02:43:32 am
content: You need an inverter of some sort, like an H bridge connected to an oscillator.

author: mattintc
author_rank: Newbie
timestamp: May 05, 2013, 02:44:29 am
content: thank you! finnaly im getting somewheres. This telephone transformer is also 4A rated

author: mattintc
author_rank: Newbie
timestamp: May 05, 2013, 03:00:41 am
content: Anymore brains that i can poke at for an idea?

author: Rerouter
author_rank: Super Contributor
timestamp: May 05, 2013, 03:12:42 am
content: as the contactors should not care about it being sine wave driven, the H bridge approach should work just fine,have an oscillator, divide it down to close to your desired frequency, feed that into not gate to invert for the other channel, then you could then either use a npn with a pullup resistor for each side to switch on and off the respective side, or a high side buffer chip so that it can directly drive the sides at your input voltage,the whole theory being, part 1 of the cycle, one sides input is high, turning on the npn of the h-bridge and clamping that to ground, while on the other side its pulled low turning on the pnp and clamping the other side to +24V, and for part 2 of the cycle, the process is reversed, resulting in a square wave shaped +-24V waveform which is the same in terms of wattage as a 24V RMS sine wave,

author: mattintc
author_rank: Newbie
timestamp: May 05, 2013, 03:17:08 am
content: wow that was some new terms for me but i got the jist of it all. thank you sir.
Converting Elenco XP-720 to 240V - Page 1
Forum section: electronics / beginners

author: Irukanji
author_rank: Contributor
timestamp: November 02, 2013, 09:53:30 am
content: Hello,1st time post, I ran into a bit of a pickle. I was reading the forums and found the XP-720 was well regarded as a cheap, modable power supply which would do everything I needed. I bought it in kit form.Anyway fast forward a few days, I've been reading more about it and the little voice in the back of my head was correct; it only runs on 110-130V...fml. $65 + 25 shipping I can't refund, so I'll be doing it the hard way. An option is to purchase a cheap power pack for 240V to 110V, but I was wondering if there was a smaller solution which would fit inside the case?From reading the manual, it is 110-130V in with 17VAC and 8VAC out to power the rest of the circuitry.I guess the question is, has anybody attempted this? Is there a transformer which can take 240V and spit out 17VAC and 8VAC? Would I be better off just getting an external 240V to 110V "step down" transformer?Sorry for being a noob, I was hoping this power supply could teach me some more about how the various circuits work, but it looks like I'm going to get a lesson even before I get there....

author: grenert
author_rank: Frequent Contributor
timestamp: November 02, 2013, 03:26:53 pm
content: Note that the 17VAC is a dual 17VAC (i.e., 34VAC center-tapped), one each for the +15V and -15V variable outputs.So, to supply those outputs as well as the 5V fixed output, you will need to find a triple output transformer.Here's an example of one:http://mcitransformer.com/i_4-06_2.htmlThis is a USA company, not sure if their products are available overseas, but someone out there probably makes a similar product. Of course, you need to make sure you find one with sufficient current output for the task. The ones I linked to look a little weak (only max 500mA at 15V).Note that the Elenco transformer also has extra taps on the 17VAC secondaries for the 12.6VAC center-tapped outputs. I don't think you'll ever find a non-custom transformer that will include those. So, you will lose that function when you replace the transformer

author: Irukanji
author_rank: Contributor
timestamp: November 02, 2013, 03:42:50 pm
content: I can't win lol. Might just go the step-down transformer for 240 to 110V and be done with it. It'd save a lot of hassle, and as you mentioned I doubt I'd find an off-the-shelf transformer like the one in the kit. I guess one day I'll know what voltages and current I use the most and make a simple circuit using an LM317 or similar.Things I've learned today; read the datasheet before deciding, it's never easy being green, and the LM317 is a nice little IC which I will experiment with when I can pick some up from the shop.

author: Whuffo
author_rank: Regular Contributor
timestamp: November 02, 2013, 05:15:26 pm
content: If you don't have step-down transformers to convert 240 to 120 already, one or more of these is a wise investment. I've got four of them; two are used regularly.Just keep in mind that they're autotransformers and don't provide any isolation. That may or may not be a problem; beware!
Converting high Z meter to low - Page 1
Forum section: electronics / beginners

author: ksat44
author_rank: Contributor
timestamp: January 24, 2024, 12:10:27 am
content: Just wondering if there might be a simple hack to convert a high impedance clamp meter I have to go low in order to get rid of the ghosts and phantoms... I love my meter, but it doesn't offer that newfangled feature the current crop have.

author: bdunham7
author_rank: Super Contributor
timestamp: January 24, 2024, 12:48:28 am
content: https://www.fluke.com/en-us/product/accessories/adapters/fluke-sv225To get the low Lo-Z you basically connect a PTC thermistor and a resistor in series across your inputs. You might use a YS4020 PTC (or two in series) plus a 1K surge-rated resistor like the OX102KE.https://au.mouser.com/datasheet/2/18/amphenoladvancedsensors_YS4020-1157120.pdfhttps://au.mouser.com/datasheet/2/303/res_ox_oy-3082554.pdf

author: ksat44
author_rank: Contributor
timestamp: January 24, 2024, 01:47:13 am
content: Can always count on good, old Fluke to sell something worth $10 for over $100+.Thanks for the reply.

author: coppercone2
author_rank: Super Contributor
timestamp: January 24, 2024, 02:05:54 am
content: its because of the enclosure being good / sealed / tested.I think a fair price would be like 60$It does need to go through testing. That makes it worth while. But the low price components makes it too expensive.

author: ksat44
author_rank: Contributor
timestamp: January 24, 2024, 03:11:29 am
content: This might be an overly simplistic, but would something like an incandescent light bulb connected between the meter input leads take care of this problem?

author: bdunham7
author_rank: Super Contributor
timestamp: January 24, 2024, 03:24:36 am
content: Quote from: ksat44 on January 24, 2024, 03:11:29 amSort of, but it will only work properly at one voltage and the parameters will be different, much lower on resistance with even the smallest of bulbs.

author: ksat44
author_rank: Contributor
timestamp: January 25, 2024, 05:48:56 am
content: I'm not looking to totally eliminate the ghost voltages, just reduce them to levels that when I see them I know what they are. I just plan on doing this on in a residential wiring setting, so seeing something like 17 Volts instead of 100 would still be useful to me. From what I've heard, most typical dual impedance DMMs operate much the same way, though I've never used one personally.When taking measurements working in the low Z mode. I wouldn't be using the bulb when taking resistance measurements, if that's what you were referring to.

author: bdunham7
author_rank: Super Contributor
timestamp: January 25, 2024, 06:10:24 am
content: What I meant was that 1) you'd have to use bulb suitable for the voltage you are measuring--a 120V bulb will pop if you use it on a 240 or 480V circuit and 2) the bulb will have a lower resistance than a typical Lo-Z meter which (for Fluke) is usually about 3k-ohms cold and a lot more hot. If you understand all that, then yes a bulb is a possible solution. But if you're making something anyway, a resistor and a PTC or two aren't all that expensive.
Converting NiMH battery to Li-ion in mobile phones - Page 1
Forum section: electronics / beginners

author: bialasikk
author_rank: Newbie
timestamp: January 02, 2017, 12:10:02 pm
content: Hi!I love old mobile phones. I have really huge collection, but sadly really big part of them have NiMH batteries (and most of them are dead now).It's really annoying because I have a lot of phone's batteries from newer phones; most of them are Li-ion. Cells inside are perfect in dimensions but it's totally another type of battery - another levels of charge, another algorithm for charging...I have a question - is it possible to make a NiMH -> Li-ion converter? It will be small board which will be a 'bridge' between old charging system in phone and new cell inside battery. If it's possible, have you got any ideas how can I make it?Thanks,MarcinPS. that my first post here, main Polish electronics forum (elektroda.pl) is really unfriendly for new users and questions like this, so nice to be here!

author: jeroen79
author_rank: Frequent Contributor
timestamp: January 02, 2017, 04:08:53 pm
content: I suppose it is possible.You will need to make a two way dc dc converter that will on one side (dis)charge the Li-Ion within it's limits and on the other side mimic a NiMH, taking a (presumably) constant current charge and then doing something to indicate that it is full.Without knowing how exactly the phone does the charging this will be difficult to get right.Can you not find new NiMH cells?They're not extinct yet.