hybridfree/eevblog-posts huggingface dataset:
Maximum input voltage value of the oscilloscope and probes - Page 1
Forum section: electronics / beginners

author: ElecroBIT
author_rank: Newbie
timestamp: January 29, 2024, 03:50:29 pm
content: Hello Everyone,I'm new to electrics so please tell me if I'm wrong in my thoughts about themaximum input voltageof the oscilloscope and probes.Oscilloscope Hantek 2C42Input Protection Voltage: 150V RMSTherefore, the maximum voltage that can be measured with an oscilloscope with a 1X divider is:150 (Vrms) = 424 (Vp-p/peak-to-peak) = 212 (Vpk/amplitude) = 150 (Vdc/DC voltage)Probes (Maximum input voltage):Hantek PP80B 80MHz1X: 150V RMS10X: 300V RMSTherefore, the maximum voltage that can be measured with this probe with a 10X divider at a frequency ≤ ~18 kHz is:300 (Vrms) = 848 (Vp-p/peak-to-peak) = 424 (Vpk/amplitude) = 300 (Vdc/DC voltage)P6100 100MHz1X: 200V Working Voltage (Vp-p)10X: 600V Working Voltage (Vp-p)Therefore, the maximum voltage that can be measured with this probe with a 10X divider at a frequency ≤ 40 kHz is:212(Vrms) = 600 (Vp-p/peak-to-peak) = 300 (Vpk/amplitude) = 212 (Vdc/DC voltage)P4100 100MHz100X: 2000V Working Voltage (Vp-p)Therefore, the maximum voltage that can be measured with this probe with a 100X divider at a frequency ≤ 40 kHz is:707(Vrms) = 2000 (Vp-p/peak-to-peak) = 1000 (Vpk/amplitude) = 707 (Vdc/DC voltage)1. Am I right or wrong?2. What does the Y-axis (VAC) mean on a graph: is it (Vpk/amplitude) or (Vp-p/peak-to-peak) or something else?3. Please explain what does (DC + AC Peak) mean?4. What is usually meant by the phrase: the maximum voltage of the probe is 600V?Does this mean 600V (Vpk/amplitude) or 600V (Vp-p/peak-to-peak)?Hope, my questions are clear enough.Sorry for my bad English skill.Thanks in advance for help.
Maximum noise shaping order - Page 1
Forum section: electronics / beginners

author: fonograph
author_rank: Frequent Contributor
timestamp: October 16, 2017, 02:33:05 pm
content: There is music format introduced in the 90s by Sony called DSD,its 1 bit pulse density modulation with 7th order noise shaping,it runs at 2.8MS/s.There is also DAC from company called Mola Mola that uses 7th order noise shaping to convert the incoming 16bit 44100KS/s pulse code modulation into 100 MS/s 1bit pulse width modulation.Why 7th order? I understand that in sigma delta ADC its hard to design high order noise shaping becose it must be analog,that means IIR filters only,that means feedback and stability problems as the order increase so they are mostly around 4th order,atleast thats what I saw I am no expert on sigma delta converters.But this is all digital domain,FIR filters.... instability,not even once,engineering challenges,not even once.With modern computers its not any harder to make 8th order or 9th order that it is to make 7th order.Why its 7th order? Why not more?For each increase of the noise shaping order,the more dynamic range we get at low audio frequencies.What is the reason to choose 7th order? Since this is digital noise shaping and filtering,isnt higher order noise shaping simply better? Are there some negatives that I dont know about?I get that at 16bit 44100 KHz noise shaping,you cant go crazy on the noise shaping filter order becose there is like 1/6th of octave above 20KHz to push the noise into inaudible region,but the dsd is running at almost 3 MHz,thats many octaves to push that noise into,and the Mola dac is running st 100 MHz,I just dont see the reason why 7 is such magical number when it comes to noise shaping.It sort of triggers me becose I am obsessive even order binary perfectionist,I would if anything expect it to be 8th order.

author: tszaboo
author_rank: Super Contributor
timestamp: October 16, 2017, 02:42:28 pm
content: 7x20dB is 140dB. You never hear that big dinamic range.

author: fonograph
author_rank: Frequent Contributor
timestamp: October 16, 2017, 02:48:58 pm
content: Quote from: NANDBlog on October 16, 2017, 02:42:28 pmI dont care if its audible or not,I dont even care about that music format or dac.I only want to know if its possible to make higher order noise shaping,and what are negatives of higher order noise shaping.And even the argument that why put higher order when 7th order is already good enough for 140db,I ask then,why they didnt make the sample rate half and increase the order to get the same dynamic range? If there are no negatives or limits to digital noise shaping filter order,it doesnt make sense to use anything less than maximum filter order in order to use as low sample rate as possible to minimize the audio file size.
Maximum power from a transformer? - Page 1
Forum section: electronics / beginners

author: d4n13l
author_rank: Regular Contributor
timestamp: August 27, 2018, 09:46:59 pm
content: Hi,I've been working on a power supply design. I have a 24V 5A transformer from which I can get ~35V once rectified. However I understand I won't be able to get the 35V 5A.Can I calculate the max power is possible/safe to draw from this transformer?

author: Ian.M
author_rank: Super Contributor
timestamp: August 27, 2018, 10:07:55 pm
content: Almost certainly *No*, because you don't have any data on how much the voltage will drop when loaded, including rectifier losses, nor do you have data for its short-term overload ratings.However, the current derating factor for a bridge rectifier directly feeding a reservoir capacitor is 0.62, so your 5A RMS secondary is only good for 3.1A DC out if that's your configuration. See Hammond (transformer division)Design Guide for Rectifier Usefor derating factors for other configurations.

author: ArthurDent
author_rank: Super Contributor
timestamp: August 27, 2018, 10:27:43 pm
content: 24 volts times 5 amps means you can get a maximum of 120 watts from the transformer. If the output is bridge rectified and connected to a capacitor you will get a maximum voltage of about 35 VDC, no load. Once you put a load on the output the voltage will drop and because of voltage drops across diodes, etc., you cannot expect to get the maximum 120 watts out. As a rough guess I’d say you might get 30 VDC at maybe 3 amps but an unregulated supply like this is of little use for a workbench supply.If you need a bench supply and don’t have a lot of experience building stuff, it might pay to buy a used or new supply from Ebay or Amazon that will do what you want.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 28, 2018, 11:40:23 am
content: Quote from: ArthurDent on August 27, 2018, 10:27:43 pmCareful -- you're correct up to here, when PF = 1. Otherwise, the general truth is 120 VA of capacity.QuoteA FWB rectifier, with cap-input filter, typically has PF ~ 0.5, so you should expect 120 VA * 0.5 PF = 60 W available output. About 2A DC would be reasonable.Think of it as the price you pay for getting extra voltage out.(Indeed, the price is even worse if you use a doubler, say. There, PF can be ~0.2.)You can always run more, of course, either for higher operating temperature*, or for short durations since the temperature is effectively averaged over a long period of time (minutes?). A momentary load of 4 or 5A DC might be acceptable, say for CNC controller or audio amp applications, since the average will tend to be lower.*Given suitable considerations. Like, will ambient temperature always be modest? Or is there a fan? Or is lower operating lifetime acceptable? That sort of thing.Tim
Maximum Ratings of Big Electrolytic Capacitors? - Page 1
Forum section: electronics / beginners

author: KerimF
author_rank: Frequent Contributor
timestamp: February 11, 2025, 12:10:18 pm
content: For an electrolytic capacitor, the maximum rating of its voltage (the breakdown voltage) is given.Is there also a maximum rating of current (thebreakdown current)?Is there perhaps a maximum rating ofdissipation?About the breakdown current, let us assume we have a4700uF 35Vand itsESR = 50 mOhmIf this capacitor was discharged then connected to a power voltage source of 1V, the initial current will be 1/0.05 = 20A (neglecting the parasitic resistances).But if it will be connected to a 12V acid battery, the initial current will be much higher, 12/0.05 = 240A.Although the voltage is much lower than 35V, I have the impression that this test will damage the capacitor. I mean, if I am not wrong, there is likely a rating for the maximum current which shouldn’t be exceeded too.Any idea?Thank you.

author: RoGeorge
author_rank: Super Contributor
timestamp: February 11, 2025, 12:25:16 pm
content: Yes, there is a max current. Usually the Imax is specified in the capacitors' datasheets, or in the application notes, depending on each manufacturer. Here's a random datasheet example, see the tables at page 5 of 9:https://www.mouser.com/catalog/specsheets/epcos04390-1.pdf

author: David Hess
author_rank: Super Contributor
timestamp: February 11, 2025, 01:27:03 pm
content: Quote from: KerimF on February 11, 2025, 12:10:18 pmMaximum current is not usually specified, but dV/dT may be. I have never seen it for aluminum electrolytic capacitors.Dissipation matters however this is usually specified indirectly with maximum ripple current, which is a function of surface area for heat dissipation, equivalent series resistance, and maximum operating temperature.
Maximum transient current through a transistor? - Page 1
Forum section: electronics / beginners

author: dsegel
author_rank: Contributor
timestamp: August 18, 2017, 05:14:10 pm
content: I have an application where I want to switch a path through a transistor that will be +/-20V and may go up to 2A. The current will only be flowing for about 100ms, with at least 1 second in between. I'm currently planning on using a ULQ2003A transistor array because I need 6 of them to control 6 devices independently.My question is, how do I know if this will work, or if I'm going to blow up the transistors? The datasheet for the ULQ2003A is here:http://www.mouser.com/ds/2/389/ulq2001-957368.pdfIf necessary I could lower the voltage a bit.

author: Zero999
author_rank: Super Contributor
timestamp: August 18, 2017, 05:51:21 pm
content: The data sheet specifies a peak current of 600mA.Another issue you may have is that the Hfe of the transistors might not be high enough to give a low enough on voltage. The transistor might operate in its linear region acting like a current sink, dropping most of the voltage, leaving very little for the load.

author: BigBoss
author_rank: Regular Contributor
timestamp: August 18, 2017, 06:05:15 pm
content: Quote from: dsegel on August 18, 2017, 05:14:10 pmIf you application is purely to switch a signal during 100ms, I recommend you to use Switching MOS Transistors.They have more current carrying capability and higher dissipation capacity on them.http://www.onsemi.com/PowerSolutions/product.do?id=FDMQ8403It's got 4 channels.

author: dsegel
author_rank: Contributor
timestamp: August 18, 2017, 06:19:21 pm
content: Yeah, i just read up on Hfe and realized it might be a problem.I saw the 600mA spec, but didn't know if that applied to transient events.

author: dsegel
author_rank: Contributor
timestamp: August 18, 2017, 06:21:20 pm
content: Thanks, I'll check it out.

author: danadak
author_rank: Super Contributor
timestamp: August 21, 2017, 12:14:31 am
content: Google "octal power driver", a number of alternatives. Darlingtons suck because theyhave such high Vcesat.Regards, Dana.
might be my LCR meter damaged ? (DE-5000) - Page 1
Forum section: electronics / beginners

author: ammjy
author_rank: Regular Contributor
timestamp: December 11, 2019, 10:35:34 am
content: Hello,I have a DE-5000 LCR Meter.when I measure the internal inductance of RC BLDC motor, I've rotated motor almost 180 degrees with fast speed by hand to check differences.But, after that, I realized something was wrong,,So, I was so worried and when I have tested same condition, BLDC motor momentarily made 0.3 Vrms and 1 to 2 A.Might be, because of this behavior, my DE-5000 LCR meter might be damaged ?and Attached screenshot is measured result when motor rotated by hand.Vrms values is between 300 ~ 700mV.
May I have damaged my Brymen BM789? - Page 1
Forum section: electronics / beginners

author: EL34
author_rank: Newbie
timestamp: January 17, 2025, 07:20:13 am
content: Hello.I was about to measure voltage on the wall socket and due to an error instead of connecting phase and neutral I connected one of these with earth, so the measure was ~ 125V. Stupidly, in a hurry and without thinking twice, and since I didn't found a warning in the manual, I repeated this operating using the Auto Voltage (LowZ) and the lights of my house went out.The multimeter seems to work fine measuring V~ and DC V and the results seems to be as accurate as before. I measured an used 9V battery in DC mode, it gives ~7.1V (this is the correct value), in AutoV mode I get ~3V and the number is decreasing. Apart from this I've not noticed any ill sympton from the device, no magic smoke or wrong behaviour.What are the odds I've damaged my Brymen?

author: Chalcogenide
author_rank: Regular Contributor
timestamp: January 17, 2025, 08:43:19 am
content: The Low-Z mode is designed to handle line AC voltage with no problem; by connecting phase to ground via the Low-Z you tripped the RCD/GFCI because the low-Z impedance allows enough current flow to trip an RCD/GFCI. The low-Z is a PTC with initial cold value of about 3 kOhm, so at 125 V you get about 40 mA which is over the trip threshold of a domestic RCD.Your low reading of the battery in low-Z mode is probably because the battery is pretty depleted and with 3 kOhm load it gets loaded down to 3 V. I would say your meter is fine.

author: EL34
author_rank: Newbie
timestamp: January 17, 2025, 10:02:21 am
content: That makes sense, thanks so much for your insight.
May I speak here? Hello everyone - Page 1
Forum section: electronics / beginners

author: wonderful
author_rank: Newbie
timestamp: December 24, 2014, 10:02:17 am
content: I am working in Shenzhen Wonderful Technology Co.,Ltd was founded in 1996, Located in Shenzhen Guangdong Province, China. We specialize in manufacturing and selling high-precision, high-density double-sided PCBs and multilayer PCBs.I want to have some friends in here, also in PCB industry?Would you like to tell something with me?

author: tautech
author_rank: Super Contributor
timestamp: December 26, 2014, 07:30:06 am
content: Welcome to the forum.I have linked your other post that contains your website:https://www.eevblog.com/forum/chat/new-member-please-introduce-yourself/msg574883/#msg574883Feel free to add your website URL to your forum profile for further promotion of your PCB services.

author: taitny
author_rank: Newbie
timestamp: October 22, 2024, 02:04:58 pm
content: Are you still in Shenzhen? I'll be visiting in early January. Looking for interesting places to visit.
maybe a stupid question (brymen 867) - Page 1
Forum section: electronics / beginners

author: dirk
author_rank: Newbie
timestamp: October 15, 2014, 07:36:27 pm
content: i'm new here and bought a Brymen 867 mainly based on this forum and a video review on youtube. It sure feels as a solid meter and I think it is a good upgrade from my fluke 75.But now I have question. When I look at the dc volt setting I see the option when I press the select button to measure AC and DC on the dual screen at the same time. This doesn't make sense to me.Can anyone enlighten me?

author: tautech
author_rank: Super Contributor
timestamp: October 15, 2014, 07:48:06 pm
content: Welcome to the forum dirk.I strongly suspect it is for measuring AC ripple on a DC supply.Handy feature to see the expected DC level and the AC at the same time.It would be handy for quick checks on PSU outputs to see if the smoothing caps are doing their job.

author: dirk
author_rank: Newbie
timestamp: October 15, 2014, 07:57:42 pm
content: Thanks for the fast reply. I have a lot to learn!!!

author: Lightages
author_rank: Unknown
timestamp: October 16, 2014, 02:00:22 am
content: Yes, the option is to see DC only, DC with any AC voltage superimposed on the DC on the secondary display, or True-RMS with DC and see the AC component in the second display. These modes have different uses as Tautech says.The DC mode with AC on the secondary can be used to measure ripple and noise within the bandwidth of the meter. It can also be used to trim the bias of the output of an amplifier so that there is no DC.The True-RMS with DC can be used to troubleshoot problems where fuses or circuit breakers are blowing but you only think that there is AC present on the load but the DC offset is pushing much more power through the load.These are just some simple examples of the use of these modes.
Maynuo M9712 Elec Load Spec question - Page 1
Forum section: electronics / beginners

author: talon
author_rank: Newbie
timestamp: December 16, 2015, 01:47:36 am
content: Hi, I'm playing around with the M9712. I have it hooked up to a 1.5 AA cell and set to CR.The display switches from CR to Unreg when I get up to about 63 ohms. I checked the specs and it says,"CR Mode (Voltage and current input value >or= to 10% full measurement) What does this mean ?Since I can place the cell across a 100 ohm resistor and measure the current I'm starting to wonder if something is wrong with the M9712.Please help with my ignorance, thank you.

author: talon
author_rank: Newbie
timestamp: December 18, 2015, 12:39:39 am
content: I think I figured it out. Unreg is not necessarily an error condition. It just means that the load doesn't need to regulate (reduce) the current. At the larger R values it needs as much current as it can get so it adjusts the voltage(up to the max voltage of the supply/cell) to meet the CR value.I still don't know what full measurement means.OTOH I might be off base here.
Mbus impelmentation - Page 1
Forum section: electronics / beginners

author: ElectricBananaHand
author_rank: Newbie
timestamp: April 08, 2024, 06:38:51 pm
content: Hi!I am trying to do my own implementation to read data from electric meters that use the Mbus protocol. Been searching for quite a while and found this sitehttps://domoticx.com/m-bus-hardware-components/I have tried to simulate this here:https://falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWcMBMcUHYMGZIA4UA2ATmIxAWIosgoFMBaMMAKADcQ9sVxieueYFHiiiALLWxjRtGAhYB3TtxDFCIDIRFqoikIQmr1B2mE26ATvsNnjhlCmmTccFlc0iwY6R949aDvCQer4O0gIgYbpKvjqEGDw6wUomkY7Wkmi6AC4aCDzYWhqQ0oUipiBM0GRieHhYuGGEcISMIgwo0BhqYKQ4xAhCYgOMVGBwIAAmdABmAIYArgA22SElINj5+gkbWyh6qZs8h1nJGkVleQVFZ76XvhKybucijy8gYgaiBCFFnz5-JIsADm72G6l8+XK0WKpTwPnW4N0oIwiJ0qOkUJkBx2cUMQJSOyOGV2-gOhmJqTEKmCVipKipeFkGxcIJJg2OhixTxSFK2HNJMIFxIFSLOop02HhHyBVil0iR3FoYuQrlBSpl6hQCHUKrO3m0utqfksH2NvR4BsiOtE2GI8D0Vp0FqMMKt2qNImE5Udxu9ZpE2EKpqtQc9G2lATQaoDEYVxrEYHUPOUPCiERdZwzwlTrtuRRdoXS+c83neBNj-su-rOYcidQ2RRrbKrTYbbyeuRduGkVfWFQ60EISfwQk0tQSCAQo0iQ5HqMIRDEGGpjHI41o03my1WSn9VeDzb3DY1rZ9MQu6zuN1+XsMRact8iO1Chluh-bfobwVyOC1DdCb9KggTp4kgXopEKQgpBQYg8DXFlqlIZDBi4SAECDVUplmRYVnJWgdCdZN8IoIQSVqJ4gAThere are a few question about this.1. Why is not current flowing to A(point between 33K and 3.3K) and B(point between 39K and 22K) aswell, it looks to me that there is a path to ground?2. I was expecting the voltage at A to be at approx. 3V and B to be 12V, not in the millivolts range..According to the protocol and also what I have seen on an oscilloscope, is that during data transmission the voltage will switch from 34V-->22V. 34V should be interpreted as a 1 and 22V as a 0.Is this what suppose to happen in the circuit that is found in the link? That during a low signal, Q2 will open and current will not flow to RX and input will read 0.I feel like I'm stumbling in the world of electronics, so please If I am missing any fundamental concepts, teach meThanks!

author: m k
author_rank: Super Contributor
timestamp: April 13, 2024, 07:20:59 pm
content: When Q3 is not conducting the MBus is floating.But there can be other parts of the bus that pulls the 34V down, more or less.Overall configuration of current driven thing goes so that all loads are a one serial thing.When voltage driven thing has loads in parallel.If current driven thing is say 20mA the voltage of the bus is what ever is needed that this 20mA is maintained.That way the communication may be slow but it's also noise tolerant.Here Tx high is pulling MBus- low from it's resting level.This is clearly a half duplex implementation, local Tx and Rx are connected, normal stuff also.It goes so that master is giving one slave a right to communicate.It goes also so that 34V is not sourced from many places, usually.Change voltage source to its original place and replace the current one with a resistor and a switch.
MC1466Lvs lm723 - Page 1
Forum section: electronics / beginners

author: ME
author_rank: Frequent Contributor
timestamp: June 08, 2025, 03:55:46 pm
content: can an lm723 be used inplace of the MC1466lvs? in a psu .

author: wraper
author_rank: Unknown
timestamp: June 08, 2025, 04:08:14 pm
content: No.

author: chilternview
author_rank: Frequent Contributor
timestamp: June 08, 2025, 04:12:19 pm
content: Not directly, they are not the same pinout for starters.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 08, 2025, 04:21:13 pm
content: It is not just a different pinout, but also different function. The MC1466 has 2 error amplifier, like for a lab supply with CC and CV mode. The 723 has only 1 main error amplifier and a simple transistor for a crude current limit, like in a voltage regulator.The reference voltage is also different (7 V in 723 vs some 18.5 V in MC1466).One may use 2 or 3 of the 723 to create a somewhat similar function.

author: coromonadalix
author_rank: Super Contributor
timestamp: June 09, 2025, 12:34:18 am
content: mc1466 can do higher voltages than 723, unless you use the 723 in a floating designthere was an mc1566 too and i think it could do 10v moretheses ic's are very rare and almost unobtanium, many fakes around

author: floobydust
author_rank: Super Contributor
timestamp: June 09, 2025, 02:32:44 am
content: A MC1466 remake using SMT discrete transistors,PCBfrom OSHPark. To keep some Lambda power supplies going.https://tubetime.us/index.php/2014/09/28/a-miniaturized-discrete-mc1466/

author: MarkL
author_rank: Unknown
timestamp: June 09, 2025, 02:44:44 pm
content: Lambda used the MC1466L in many of their old power supply designs and re-labeled it with an internal part number, FBT-031 (aka FBT-00-031).If you really want to build this old design, you can still buy FBT-031 on ebay from a couple of sellers for USD$10. I bought some from "Retro-tech-n-cool" (no affiliation) for repair work a few months ago and verified that they do work properly. I would NOT purchase this part from China sellers.
MC148x to Max232 Questions - Page 1
Forum section: electronics / beginners

author: Vivis
author_rank: Contributor
timestamp: March 01, 2022, 07:43:33 am
content: Hello all.I'm trying to redesign this very old circuit that uses a 1488 and 1489 to use the slightly less archaic Max232.Here is the old circuit:Here is the Max232 pinout:This is what I came up with after trying to combine the two:Does everything look kosher? I know some of it may not be %100 necessary (maybe the optocoupler isn't needed), but I figured it wouldn't hurt to try to stay faithful to the original design. Since I'm usually well within the digital domain, this is a bit out of my comfort zone (its also the first circuit i've designed!).

author: jwet
author_rank: Frequent Contributor
timestamp: March 01, 2022, 03:41:53 pm
content: A couple things that I noticed-Ground on a DB-9 type 232 port is Pin 5 (not 7 as in DB-25)You probably need a 10k or so pullup on pin 11. The 1488 provides something like this, the Max232 has an approx 400k pullup and might not be enough.

author: Vivis
author_rank: Contributor
timestamp: March 01, 2022, 07:23:26 pm
content: Whoops, thanks for catching the difference in ground pins, that was just user error.The pull-up resistor is definitely something i wouldn't have thought of, seeing as I don't even know the use for one. My basic electronics knowledge is pretty dismal; I spent all my time learning digital logic so far.To clarify, would that be a 10k from pin 11 on the Max232 to +5 to keep pin 11 high? I can see the 400k on the 232 diagram. Would it hurt anything to try the circuit without it and add it in if the circuit doesn't work?Thanks a ton for the advice.

author: jwet
author_rank: Frequent Contributor
timestamp: March 01, 2022, 07:31:55 pm
content: It wouldn't hurt to try it but it likely won't work. The output of Opto is an open collector.I was also thinking- why not use a FTDI FT232 chip instead of the MAX232- you'd get USB serial which is probably more useful unless you're already setup for 232.

author: Vivis
author_rank: Contributor
timestamp: March 01, 2022, 07:44:51 pm
content: Lol; it's going to get plugged straight into an FTDI serial to usb converting cable, at least for testing. I need to keep it serial for backwards compatibility. Some of the application discussed for this might be using it with an old dumb terminal or other equipment of yore. A lot easier to use off the shelf cables to go from serial to usb.Thanks again for the advice. Now i know where to look when i put it together and it doesn't work.
MC34063 - Inverting conf not working properly - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: May 22, 2022, 10:02:40 am
content: Hi,I'm trying to design a circuit around the inverting configuration of MC34063, a bit for fun, a bit to understand the basics for a new project I am undertaking.The idea is "simple" I have a 3.7V power supply (currently: my bench psu) and I have to provide (-)3V on the output capable of 300mA. 500mV ripple would be great.Using a bit of math and mostly an online tool I came out with the following values for the components of the standard circuit:Code:Ct=223 pFIpk=1356 mARsc=0.221 OhmLmin=11 uHCo=30 uFR1=1.3k R2=1.8k (2.98V)and designed a first draft circuit (which achieves a bigger output voltage, but I currently don't have the required resistors)The problem is that the only output current I can get is around 20-30mA before the voltage collapses.What have I done wrong?thanks

author: capt bullshot
author_rank: Super Contributor
timestamp: May 22, 2022, 10:14:41 am
content: 10uH for the inductor appears a bit too much on the low side to me.The 34063 is from the generation of converters that usually work with 100uH to 1mH inductors.

author: Moriambar
author_rank: Unknown
timestamp: May 22, 2022, 12:08:36 pm
content: Quote from: capt bullshot on May 22, 2022, 10:14:41 amHi, thanks for your reply.I tried swapping the inductor for bigger ones (up to 10mH). Negligible changes...

author: mikerj
author_rank: Super Contributor
timestamp: May 22, 2022, 12:18:37 pm
content: Both the inductor and the 47uF output cap are very low in value for this configuration, should be ~10x that. Are your inductors rated for the peak current they will see without saturating?

author: Moriambar
author_rank: Unknown
timestamp: May 22, 2022, 02:53:15 pm
content: Quote from: mikerj on May 22, 2022, 12:18:37 pmHi, I tried putting a 1mF and 220uH components to no avail.And regarding the inductors… that's a good question, probably that's the main problem: I have only some generic ones bought from aliexpress some time ago.Thanks, I guess. I think I'd better try and move on to the next circuit, which will have an actual use, and buy better components.

author: kevin original
author_rank: Contributor
timestamp: May 24, 2022, 09:41:33 pm
content: Try adding more input capacitance on Vin, like 100uF or more. The inverting configuration draws lots of peak current on the input.
MC34063 issues - Page 1
Forum section: electronics / beginners

author: Medo
author_rank: Regular Contributor
timestamp: August 26, 2011, 04:41:54 pm
content: I tried to design 24V to 5V converter around MC34063 but I have stumbled upon some problems.By all calculations I should get easy 5V but I measure over 8...Could it be problem that I am using only few mA usually?Board should work from cca 1-250 mA...I dare not put PIC on this board before I am sure that it will not go out...Do you have some generic component values for 24->5 conversion that would work with L=150uH?Data I calculated is:R1=1.2KR2=3.6KCt=1500pFRsc=0.68L=150uHCo=470uF

author: Simon
author_rank: Unknown
timestamp: August 27, 2011, 12:01:05 pm
content: what is the frequency ?I put your data intohttp://dics.voicecontrol.ro/tutorials/mc34063/calculate.phpassuming 100KHz and got some very different values, you may want to recheck your calculations

author: Medo
author_rank: Regular Contributor
timestamp: August 27, 2011, 11:46:33 pm
content: Quote from: Simon on August 27, 2011, 12:01:05 pm70 kHz

author: Medo
author_rank: Regular Contributor
timestamp: August 28, 2011, 06:25:13 pm
content: Yep, I made "factor of ten" error in my spreadsheet...Thanks!
mc34063 ltspice not simulating - Page 1
Forum section: electronics / beginners

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: January 11, 2019, 06:21:37 am
content: not sure why its not simulating this boost circuithttps://nofile.io/f/mxmk6ODZVvm/27v-boost-mc34063.zip

author: iMo
author_rank: Super Contributor
timestamp: January 11, 2019, 10:57:04 am
content: Replace your ".tran 1" with this in your schematicsQuoteRemove and insert L1 again.Replace Diode with 1N5819.

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: January 11, 2019, 12:39:58 pm
content: Quote from: imo on January 11, 2019, 10:57:04 amSame circuit in the screenshot results in error. The error node is the timing capacitor to IC pin.

author: Ian.M
author_rank: Super Contributor
timestamp: January 11, 2019, 01:47:03 pm
content: Who in their right mind hides component designators in a sim?You don't need the .inc MC34063.lib as that's built into the symbol.It looks like the MC34063 model has a problem. If you don't use the .tran startup or uic options the operating point analysis at the beginning of the .tran run can leave it stalled in a non-oscillating steady state. There are other models in the .lib file that may be worth trying - edit U2's value (currently MC34063) to select them.Choosing a realistic model for the diode (e.g. 1N5819) helps with timestep problems as does setting initial conditions for the two big capacitors so the massive initial charging current surges aren't included in the sim. Label the Vcc node, then use:Code:.ic V(vout)=11.5V V(vcc)=12VIt then runs OK (under LTspice IV) with default settings and no.options overrides, with a simpleCode:.tran 100m uic

author: iMo
author_rank: Super Contributor
timestamp: January 11, 2019, 02:48:19 pm
content: Download the source from my post above. It should work fine.It could be I've been using a different symbol.Below from the downloaded .zipPS: I've been using Rsc=0.22ohm in my simul, it works fine with your 1.75ohm as well.

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: January 11, 2019, 10:38:32 pm
content: Replacing the 12v voltage source caused it to work. Apparently the voltage source built in resistance caused issues. The circuit boosts as it should.I prefer the symbol I modified which is more accurate to the actual device pin orientation.
MC34063 question - Page 1
Forum section: electronics / beginners

author: willbanks
author_rank: Contributor
timestamp: June 24, 2017, 11:44:20 pm
content: lets say i want to make a step up circuit with a 34063, like on page 5 of the datasheethttps://www.onsemi.com/pub/Collateral/MC34063A-D.PDFso I have a positive voltage out (right?), I know where that would go. But what about negative voltage? Do I need to construct a separate circuit to get an inverted voltage? Or would I use ground to substitute for the negative voltage?

author: Audioguru
author_rank: Super Contributor
timestamp: June 25, 2017, 12:13:57 am
content: Why do you need a negative voltage? Most circuits are powered with a positive voltage and 0V. The 0V is usually the ground in the circuit.

author: willbanks
author_rank: Contributor
timestamp: June 25, 2017, 01:01:14 am
content: ok so it would be the ground in the example circuit. i was thinking of AC! just now realized that. yeah i meant DC. thank you!
MC34063 R1-R2 purpose and value - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: May 21, 2022, 08:43:41 am
content: Hello,recently I started playing (again) with theMC34063trying various configurations.What I cannot seem to understand from the datasheet is the purpose and values of R1 and R2 (in the example from one of the datasheets I use).Can someone please tell me and make me understand?cheers

author: bd139
author_rank: Super Contributor
timestamp: May 21, 2022, 08:46:50 am
content: R1 and R2 set the output voltage with a voltage divider. You need the desired output voltage at the top of the divider (at the output) and 1.25V at the junction between R1 and R2 for the comparator input. That’s basically it.See definition of Vout on page 11 of data sheethttps://www.onsemi.com/pdf/datasheet/mc34063a-d.pdf

author: wraper
author_rank: Unknown
timestamp: May 21, 2022, 08:47:30 am
content: Resistive divider in a feedback loop to control output voltage. You choose resistor values so divided voltage is equal to reference voltage of 1.25V with nominal output voltage. In the given circuit 5V * 1.2k/(1.2k+3.8k) = 1.2V

author: Moriambar
author_rank: Unknown
timestamp: May 21, 2022, 08:59:15 am
content: thanks guys. I was blind
MC34063 step down stability problems - Page 1
Forum section: electronics / beginners

author: little_carlos
author_rank: Regular Contributor
timestamp: May 21, 2016, 12:05:22 am
content: Hi, im using a mc34063 as a step down converter, the input is 12v and the output is 5 v at 500mA, the problem is that the regultator starts becoming very unstable, switching on and off, but it doesnt heat at all, the load is 5 relays and 5 leds.the strange thing is, that when i put a 50k resistor between pins 3 and 4, becomes stable, but the regulator turns hot, up to 70º C.what do you guys think is happening?btw, when i put the resistor i mentioned before, the inductor starts making a weird noise

author: Kleinstein
author_rank: Super Contributor
timestamp: May 21, 2016, 09:15:22 am
content: The extra resistor disturbs the oscillator. I don't know the details of that circuit part, but it's usually not a good idea, epsecilly without knowing what happens inside. It could even be oscillating to fast.For the normal operation, check the circuit. There are rules / formulas / tables on how large the caps and inductors should be. Usually the MC34063 is rather tolerant, especially as a step down. There are also different possible circuits.

author: batteksystem
author_rank: Regular Contributor
timestamp: June 01, 2016, 04:07:14 am
content: Quote from: little_carlos on May 21, 2016, 12:05:22 amCan you post your circuit? Also, what is the current load for the 5 relays and 5 LEDs? We cannot help you if we don't have the necessary information. Thanks.

author: Chris Mr
author_rank: Regular Contributor
timestamp: June 02, 2016, 12:14:35 pm
content: Adding the resistor probably increases the operating frequency but it's not supposed to have a resistor to ground there - just a capacitor.It's always a good idea to test these things out of the final circuit, using a dummy load, to check it will do what you want it to do before connecting up to the real load. I have a reel of Nichrome wire I use to make up a dummy load as required, winding it round a large ceramic tile (nice white one from last tiling the bathroom which has fish swimming on it and some 'abstract' water) and a couple of bulldog clips to stop it unwinding itself.What is the ripple current of the inductor you used (from its data sheet)?Are you using the circuit in the data sheet for the MC34063 (which is only rated at 175mA)?
MC34063 - Page 1
Forum section: electronics / beginners

author: rahandford
author_rank: Regular Contributor
timestamp: August 19, 2014, 05:09:18 pm
content: Hi EveryoneCan someone please explain the best way to calculate the power (wattage) requirements for the sense resistor in the MC34063 buck configuration. If you use the example configuration in the datasheet the sense resistor has 25v across it and if I simulate in LTSpice it has a current of about 1A, thus do I really need a 25W resistor?Your clarification would be much appreciated as this is going to be my first SMPS project.Thanks all!

author: c4757p
author_rank: Super Contributor
timestamp: August 19, 2014, 05:11:06 pm
content: Quote from: rahandford on August 19, 2014, 05:09:18 pmThe Isense threshold is about 1V - the voltage across the sense resistor should not exceed that. How do you figure 25V?

author: rahandford
author_rank: Regular Contributor
timestamp: August 19, 2014, 05:27:40 pm
content: I measured it from the simulation

author: c4757p
author_rank: Super Contributor
timestamp: August 19, 2014, 05:31:05 pm
content: That's not the voltageacrossthe resistor - the other side of the resistor is solidly connected to 25V! The voltageacrossthe resistor is 25V minus what you see...Also, since we're discussing the current through the resistor - it'd be rather nice if you didn't cut that off in your screenshot.

author: rahandford
author_rank: Regular Contributor
timestamp: August 19, 2014, 05:39:42 pm
content: Apologies!I think that I am confusing myself here.I also assumed that it must be a large wattage because of the size of the resistor in the reference design.Sorry for being so dim

author: c4757p
author_rank: Super Contributor
timestamp: August 19, 2014, 05:52:44 pm
content: Okay, that's better. No need to apologizeNow, it's a 0.33 ohm resistor, and the peak current flowing through it appears to be about an amp. That means that the peak power dissipation in that resistor is I2R, or (1A)(1A)(0.33R), or 0.33W. Not bad.You should probably consider that if the output is overloaded, the voltage on that resistor will go up to the 1V threshold. Now, the power dissipation becomes V2/R, or (1V)(1V)/0.33R = 3W. Whether you want to design for that or not is up to you. Since that's just a fault condition, I'd probably go with a flameproof resistor which won't catch fire at 3W, rather than actually using a 3W resistor.Hint: You can drag from one point to another in LTspice to measure the voltage between the two. So, to plot the voltage across R1, just drag from one end of it to the other.

author: rahandford
author_rank: Regular Contributor
timestamp: August 19, 2014, 05:59:17 pm
content: Thank you very much. I understand now.Cool trick with LT Spice, I didn't know that you could do that either.Thanks again for all your help, very much appreciated
MC34063A Optional Filter help. - Page 1
Forum section: electronics / beginners

author: RayMonster
author_rank: Newbie
timestamp: December 30, 2016, 05:57:10 am
content: Hi!I have managed to build a step up converter 10v to 20v 150ma outputIt works fine.However the output ripple exceeded the designed spec of 100mv.From the data sheet, the values for capacitor & inductor was fixed without any calculations.May i know is there a way to calculate the values for this optional filter?Thanks!

author: ali6x944
author_rank: Frequent Contributor
timestamp: January 24, 2017, 06:17:51 am
content: The output filter is basically an LC low pass filter...Google lc low pass filter calculator and u can free ur self from all the annoying calculations, also can u post ur calculations for the MC34063 converter please just so I can check with u...

author: RayMonster
author_rank: Newbie
timestamp: February 01, 2017, 02:11:52 am
content: Hi just to check if im doing this right. This is the output i have, i ripple is about 40mv ignoring those random spikes.To filter off those spikes, does adding a low pass helps resolve this?Thanks Lots.

author: ali6x944
author_rank: Frequent Contributor
timestamp: February 03, 2017, 07:34:30 am
content: Can u show me the circuit and how u are connecting the probes to it ?
mc34063a  step down overheating problem - Page 1
Forum section: electronics / beginners

author: little_carlos
author_rank: Regular Contributor
timestamp: May 09, 2016, 12:22:42 am
content: hi, so im using this buck converter as a step down, the input voltage is 24V and the output is set to 5V, the current drawn is 300mA by the circuit.the problem is that the regulator is heating a lot, what could be the cause?

author: Signal32
author_rank: Frequent Contributor
timestamp: May 09, 2016, 04:13:15 am
content: How hot is it heating up ?From the datasheet the predicted temperature rise in your case would be 35 degrees celcius above ambient -- so it would probably be around 60C

author: little_carlos
author_rank: Regular Contributor
timestamp: May 10, 2016, 12:26:07 am
content: Quote from: Signal32 on May 09, 2016, 04:13:15 amhot enough to start shutting down :S
MC34063ECD-TR How to wire it for 3.3v? - Page 1
Forum section: electronics / beginners

author: Bluestreak66
author_rank: Regular Contributor
timestamp: June 16, 2013, 01:44:21 am
content: I'm trying to build up a 3.3v power supply and would like to use a MC34063ECD-TR the input will be 24vac half wave rectified and I need 3.3v @ around 1 amp. I've looked at the data sheet and can't figure out how to size the components. The way I understand it is it uses a 1.25 volt internal reference and switches the output on if the feedback is below that and off if above? So I need to change resistor value accordingly correct? Also the inductor determines the efficiency and max output current correct? So how do i determine the value of that? Those are the two things I'm struggling with. I'll put a link to the datasheet. I know there are several swithing regulators like this one and the all look to be the same to set up. This one seems to be the lowest cost solution that fits what I'm needing. Any help is appreciated Thankshttp://www.st.com/web/en/resource/technical/document/datasheet/CD00001232.pdf

author: c4757p
author_rank: Super Contributor
timestamp: June 16, 2013, 01:47:23 am
content: Have you watched Dave's video on this? He did a pretty good video on the MC34063.

author: mariush
author_rank: Super Contributor
timestamp: June 16, 2013, 01:50:00 am
content: There's also an online calculator that's pretty good :http://dics.voicecontrol.ro/tutorials/mc34063/

author: Bluestreak66
author_rank: Regular Contributor
timestamp: June 16, 2013, 01:55:32 am
content: Totally forgot about that ill give that another watch! mariush I've been looking for a calculator like that for the past hour you are awesome!

author: mariush
author_rank: Super Contributor
timestamp: June 16, 2013, 02:02:42 am
content: I guess your google-fu is horrible.Google for "34063 calculator" or "mc34063 calculator" ...MC34063A development aidhttp://www.nomad.ee/micros/mc34063a/MC34063 Universal Calculator (open source software on Sourceforge)http://sourceforge.net/projects/mc34063uc/MC34063 Calculator Online > Step-Down, Step-Up, Inverterhttp://www.bobtech.ro/tutoriale/componente-electronice/43-calculator-online-mc34063a-mc34063-step-down-step-up-inverterMC34063 parameters calculatorhttp://ukpyr.narod.ru/calc_mc34063.htmetcAnyway, glad I could be of help.

author: Bluestreak66
author_rank: Regular Contributor
timestamp: June 16, 2013, 02:33:50 am
content: lol ya I was using the whole part number my badI got all the numbers I needed. I'm laying out my board now. Thanks again!
MC4517 DRAM - Page 1
Forum section: electronics / beginners

author: Richardcavell
author_rank: Contributor
timestamp: March 13, 2023, 01:02:18 pm
content: Hi. I’m a retrocomputing enthusiast, and I’m investigating the TRS-80 Color Computer. I’ve found a datasheet here:https://orchidsound.com/mcm4517p12-dram-16-384-bit-16k-x-1-120ns-pdip-16-motorola/I wonder if I’m reading the datasheet correctly.1. Is it correct for me to consider that the 7 bit row and 7 bit column addresses could be concatenated into a 14 bit address?2. Since the chip provides only 1 bit of memory per access, would it be typical to arrange 8 of them in parallel?3. The datasheet says that it dissipates 14 mW (Standby). What exactly does standby refer to?4. It has 3-state data output. Does this mean that the default output is high-impedance? When does it produce this output?5. It has early-write common I/O output capability. What does this mean?6. The refresh is said to be 64K compatible. I don’t understand what this means.7. Does it have to be refreshed every 2 milliseconds?8. It has a hidden /RAS only refresh capability. What does “hidden” mean?Richard

author: wasedadoc
author_rank: Super Contributor
timestamp: March 13, 2023, 02:20:33 pm
content: Why do you need answers to all those questions? If those DRAM chips were used in the computer the parameters were of concern to and were taken into account by only the original designer of the computer.Yes they have 14 address bits. The chip does does have enough pins for all of those so 7 pins double up. 7 address bits are presented to them along with a signal on the Row Address Strobe pin saying "grab these 7 as part of the address". Then the other 7 bits are presented to the same pins and a signal on the Column Address Strobe says "grab these as the other 7."Yes 8 chips in parallel to give 8 bits.Yes 3-state means the output can be high impedance so the 8 chips can be connected to another 8 such chips to have more than 16 Kbytes. And they can be connected to the outputs of the ROM chip or to outputs the keyboard chip, joystick ports etc. Only one device on the bus is enabled at any one time. Typically done with a Chip Enable or Chip Select pin.Yes dynamic RAM stores charge on a tiny capacitor for each bit. The charge leaks away so has to be rewritten frequently.

author: floobydust
author_rank: Super Contributor
timestamp: March 13, 2023, 07:00:49 pm
content: Fujitsu MB8118 is an alternate, -12 or -10 speed.
Mcclicky Tailcap Switch - Is this how it works?  - Page 1
Forum section: electronics / beginners

author: bonifacio
author_rank: Contributor
timestamp: July 07, 2023, 07:13:56 am
content: Trying to make something and just need to confirm this is how mcclicky switches work. I'm actually embarrassed I couldn't find find a diagram online. Some reason Google didn't dig into forums. All the search terms and I ended up empty handed. Found a write up but made me question myself when the writer states to solder a contact spring to the negative then slaps the positive end of the battery to it. Those wires were purple and yellow...Is this how it works?

author: GLouie
author_rank: Regular Contributor
timestamp: July 07, 2023, 02:09:11 pm
content: The McClicky is a specific type of switch, but AFAIK, your diagram is correct for most flashlights with a rear click switch. For in depth answers, you should ask on Candlepower forums or Budget Light forums.
MCM6206DJ25 (static ram) replacement (and response time problem/question) - Page 1
Forum section: electronics / beginners

author: arekm
author_rank: Unknown
timestamp: December 13, 2013, 12:26:07 am
content: Hi,I need to replace 32k x 8bit sram chip - MCM6206DJ25 (http://datasheet.eeworld.com.cn/pdf/MOTOROLA/120846_MCM6206DP25.pdf). What's best place to look for replacements? I mean sites that list compatible parts.I found AS7C256A-20JCN available here in PL (by just looking for sram chips) but it's 20ns memory while original was 25ns. Not sure if replacing with fastest response time is going to work? Also AS7C256A-12JIN 12ns (http://pl.farnell.com/jsp/search/productdetail.jsp?sku=1562910) if I order at farnell.

author: SeanB
author_rank: Super Contributor
timestamp: December 13, 2013, 06:00:14 pm
content: Faster will work, it will not worry that it is faster in many cases. Slower can work, but will be dicey depending on just how much window there is left to latch the data off the bus while it is valid. Faster will have it there sooner and will wait..

author: peter.mitchell
author_rank: Super Contributor
timestamp: December 13, 2013, 06:19:58 pm
content: The specs on the datasheet seemed fine, but the logic block diagrams looked a bit odd relating to address lines...