hybridfree/eevblog-posts huggingface dataset:
6040 4axis CNC router help - Page 1
Forum section: electronics / beginners

author: Jbenson
author_rank: Newbie
timestamp: February 29, 2016, 12:49:34 am
content: I purchased a 6040 4 axis CNC Router milling engraver from China. I'm using mach3 software which is a really cool program. The program is setup in inches.I tried the road runner example that comes with Mach3 and the first thing I noticed was that the engraving came out about an 1/8the size of what it was supposed to be. I recently purchased Vcarve, another awesome program, and using one of there programs I had the same result. The controller that came with the router is unlike anything I can find on the Internet and the manual that came with it only covers the assembly of the router itself. It has an LED display and some adjustments that you can do but I have no idea what they are. I'm thinking that since it is routing the way it is with two different programs that the controller maybe the problem. It has "jd inverter" written on it. Has anyone ran into this or have any idea what it could be. I would appreciate any help I can get.

author: Fred27
author_rank: Unknown
timestamp: February 29, 2016, 10:50:28 am
content: You might have to be a little more specific.Mach3 allows you to set the number of steps per unit on each axis. Try adjusting this.The "jd inverter" may be to control the spindle rather than the stepper motors. Don't mix these up!There are plenty of CNC forums around that might give you more useful information.

author: DroneBuster
author_rank: Contributor
timestamp: March 01, 2016, 07:28:01 am
content: Also check that your G code is in inches too.

author: collingtech
author_rank: Contributor
timestamp: March 02, 2016, 02:27:55 am
content: you need to calibrate units too, inside of your gcode translator/program (solidcam,mastercam etc) and mach 3 settings , post your mach 3 settings :0)
6040z cnc macine - Page 1
Forum section: electronics / beginners

author: Richard.Reade
author_rank: Newbie
timestamp: July 26, 2016, 06:44:06 pm
content: Hi chaps I received my 6040z cnc machine yesterday, I have coupled it to an old computer with no other programme except for Mach 3. I have followed the set up instructions I downloaded from a forum link, 2 problems arise, the first is that the Y and Z axis travel the wrong way, second the spindle motor will not operate using the Mach 3 test programme. I have set the parameters as per the instructions and have set up the emergency stop button which seems to be ok. can someone tell me how to change the direction of Y and Z and the spindle motor

author: mathsquid
author_rank: Frequent Contributor
timestamp: July 26, 2016, 07:17:04 pm
content: I'm guessing that there is a software setting in Mach 3 that will reverse the motors, but I've never used mach 3, so I can't say.However, you should be able to reverse the direction of the X and Y motors by reversing their polarity. If your motors are bipolar, determine which pairs of wires go to each coil, and reverse each pair.

author: danadak
author_rank: Super Contributor
timestamp: July 26, 2016, 07:44:20 pm
content: When you set the port/pin assignments there is a polarity setting as well.Regards, Dana.

author: singapol
author_rank: Frequent Contributor
timestamp: July 27, 2016, 01:27:47 pm
content: Perhaps to help you and us it would be better if the brand and model is known.It is strange you use a setup from a forum rather than the one the machine came with in the CD.PS you can get proper help if you ask in a cnc forum.Main page:http://www.cnczone.com/forums/Sub forum - Chinese machine page:http://www.cnczone.com/forums/chinese-machines/?s=72d833764f4d609c51a1de06ddf82308

author: cncjerry
author_rank: Unknown
timestamp: July 27, 2016, 03:39:36 pm
content: You have the step/direction control lines set incorrectly. Go to the config tab and I can't remember if it is in General or Motor Tuning. Also, there is a mach3 group on yahoo groups that is very active.
6C 2110 chip/transistor ? - Page 1
Forum section: electronics / beginners

author: electrosci
author_rank: Newbie
timestamp: June 22, 2018, 03:46:05 pm
content: hi guys. please help me, i'm searching for this component (see image)

author: Chalcogenide
author_rank: Regular Contributor
timestamp: June 22, 2018, 04:23:35 pm
content: My guess would be a TI TPS2110 Power Multiplexer in TSSOP-8 packagehttp://www.ti.com/lit/ds/symlink/tps2110.pdfCheck the circuit if it makes sense.

author: electrosci
author_rank: Newbie
timestamp: June 22, 2018, 04:32:47 pm
content: see image, red marked power section
6Lowpan Discovery  - Page 1
Forum section: electronics / beginners

author: Peili
author_rank: Regular Contributor
timestamp: April 04, 2018, 11:45:10 am
content: Hi ,i've successfully set up an RPL Border Router and a few sky-websense, it runs as expected and I'm able to access the websense nodes. The RPL border router finds its neighbour nodes. But, my problem is when i paused it then it doesn't find the edge router address and i need to reset the edge router to catch the address. How can i solve ma issue other than reset option....?
6Lowpan Discovery - Page 1
Forum section: electronics / beginners

author: Peili
author_rank: Regular Contributor
timestamp: April 02, 2018, 08:47:34 am
content: Hai, i want to develop a 6lowpan node discovery using Skymotes and rpl border router.. But the persistent discovery of neighbours are a problem.. does anyone know about this issue? please help me..
6V EDC cable not powering theodolite - Page 1
Forum section: electronics / beginners

author: rinconpaul
author_rank: Newbie
timestamp: September 02, 2019, 08:57:03 pm
content: I have a question in regard charging cable. I bought an old theodolite (20+ yrs old) The charger is stuffed. The theodolite has a 3 pin 6volt socket for external power input. The charger cable with the male plug to suit the 6V power input socket has a black, red and blue wire. I soldered two cables to the black and red and attached via alligator clips to a 6V lead acid battery. Unfortunately it won’t power the theodolite. There was one battery that came with the theodolite that carried a charge, so I know the theodolite works. What is the 3rd wire for and how do I get it the theodolite to accept an external power source? Cheers

author: Yansi
author_rank: Super Contributor
timestamp: September 02, 2019, 09:09:13 pm
content: What does an old theodolite need power for?

author: amyk
author_rank: Super Contributor
timestamp: September 02, 2019, 09:10:45 pm
content: 1. Make sure you get the polarity correct --- never trust the colours.2. A "6V" lead acid battery is closer to 7V fully charged.Check how that third connection is wired on the original battery; it could be a lower-voltage tap to supply some other circuitry, or a "presence" signal, or a thermistor, or something else entirely like a custom DRM chip/1-wire EEPROM (although I'm not sure if that was so common 20 years ago.)

author: Jwillis
author_rank: Super Contributor
timestamp: September 02, 2019, 09:19:20 pm
content: First guess would be a temperature sensor.Second guess is a communication wire for charge balancing .Third guess is a battery gas gauge.Without knowing the product it difficult to tell.

author: Jwillis
author_rank: Super Contributor
timestamp: September 02, 2019, 09:22:44 pm
content: Quote from: Yansi on September 02, 2019, 09:09:13 pmSome have self levelling ,inclination sensors and digital readouts.
6V ride on car - Page 1
Forum section: electronics / beginners

author: vk6hdx
author_rank: Regular Contributor
timestamp: October 12, 2012, 04:10:37 am
content: I've had to replace the battery in my son's 6V ride on electric toy car and noticed it has a mystery black box in series with the positive lead similar to the picture below. Any idea what this is and what is is for? Is it some sort of protection to prevent over current to the motor when stalled? Current limiting resistor perhaps?Cheers,Troy

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: October 12, 2012, 04:31:12 am
content: fuse

author: Psi
author_rank: Super Contributor
timestamp: October 12, 2012, 04:36:56 am
content: Yes, as said above, its a fuse.Flip the top off (it's hinged) and you will see a normal automotive blade fuse.

author: george graves
author_rank: Super Contributor
timestamp: October 13, 2012, 03:09:58 am
content: Oh my gosh! It's aphonefuse!Just messin' with you!
6V/20W Bulb charger & battery design - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: March 20, 2017, 01:25:38 pm
content: 1. Have to design 1 hour backup for 6V/20W bulb. Have to design a UPS based system.Bulb:http://www.amscope.com/20w-6v-halogen-bulb-for-microscopes.html2. What I am thining of using one of below:A) 7.4V/5400mAh lithium Ion battery (3.7V/2600mAh) single cell. Total 4 cellsB) 14.4V/2600mAh lithium Ion battery (3.7V/2600mAh) single cell. Total 4 cells3. A) 7.4V system voltage will vary from 5V-8.4VB) 14.4V system voltage will vary from 10V-16.8V4. Now for 6V/20W, if we consider current then it would be 20W/6V=3.33AIf I use 14.4V/2600mAh battery & use TPS564201DDCR regualtor with it, below find link designed by webbench.https://drive.google.com/open?id=0B-jbeBk3wfkWM1V0LXhSeXFkak0System state state Efficieny is 92.977%.Watts of 14.4V/2600mAh battery is = 14.4*2600mAh = 37.440WattHourAt 92.977% efficieny, Watt I will get = 37.440W_h*92.977% = 34810.5888W_hoursWatts required for 6V/20W bulb for in a hour = 20W_HSo I think this can work. & I can give 1 hour back with this system.Are the calculations correct. Will system work as per my calculations5. If I use 7.4V/5200mAh battery, I will use PWM control circuit using 555 & mosfet will be controlled.System should be such that at 8.4V of battery, PWM out will create 6V at bulb.So as battery drains outs, voltage at bulb also goes down & its glow will be dimmer.6. I think 14.4V system is good, since it will always make 6V at the output.7. Any suggestions/comments on it. COst is a concern, need to design around 1K pcs.
7 Segment Displays - Page 1
Forum section: electronics / beginners

author: Spark-Doctor
author_rank: Contributor
timestamp: November 25, 2018, 09:56:04 pm
content: When you get a 7 segment display, there is a film over the front, is this supposed to be removed, left on, do not matter, protection for ultrasonic cleaners

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: November 25, 2018, 10:03:15 pm
content: Leave it on until you mount the display in an enclosure to protect against accidental scratches, etc - then rip it off. It's only there to make sure you get it from the manufacturer/distributor scratch-free.

author: Spark-Doctor
author_rank: Contributor
timestamp: November 25, 2018, 10:07:37 pm
content: Many Thanks

author: nsrmagazin
author_rank: Regular Contributor
timestamp: November 26, 2018, 01:56:11 pm
content: Quote from: Spark-Doctor on November 25, 2018, 10:07:37 pmAnd so you don't have to clean it before you mount it on the real device and sell it. Someone else will worry about it then.
7-segment LED "die" = ? - Page 1
Forum section: electronics / beginners

author: drm1
author_rank: Newbie
timestamp: January 06, 2012, 02:38:37 pm
content: The datasheet for a large 7-segment LED specifies a maximum current "per die." Does that translate to "per segment of the display" (+/- the decimal point)?And if that's the case, what does it mean that it then specifies the maximum "reverse voltage per dice?" Presumably the given 5V max is foranydie/segment, right?Thanks for any clarification you can offer. --drm1

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 06, 2012, 03:31:17 pm
content: Large displays typically use multiple LED die in series, fewer for DP.This will usually be shown in the datasheet. As they are in series this doesn't affect current spec.

author: shebu18
author_rank: Frequent Contributor
timestamp: January 06, 2012, 03:34:45 pm
content: Why not show us the datasheet? voltage per die means voltage through one segment/one led of the display.

author: Short Circuit
author_rank: Frequent Contributor
timestamp: January 06, 2012, 04:35:12 pm
content: one die is the active element of one led, not necessarily one segment.if the thing only has leds in series than this is also current per segment,but maybe there are multiple arrays of leds in series per segment, if it's a really large display?

author: drm1
author_rank: Newbie
timestamp: January 06, 2012, 06:35:46 pm
content: Thanks for helping. The datasheet is athttp://media.digikey.com/pdf/Data%20Sheets/Fairchild%20PDFs/MANF260C,280C,460C,480C,960C,980C.pdfEach LED segment does contain five diodes in series (but only one array each), so the current specification could only mean "per segment."Thanks again.

author: shebu18
author_rank: Frequent Contributor
timestamp: January 06, 2012, 07:34:46 pm
content: At a supply voltage of 12V, 21mA per segment and a voltage drop of 1,9V(green) you will need a resistor of 120ohm put after the leds in series.(the DP needs a bigger resistor coz it is only one led) At different color the resistor could vary.
7 segments display decoder question - Page 1
Forum section: electronics / beginners

author: Lucky-Luka
author_rank: Unknown
timestamp: October 19, 2020, 10:29:41 am
content: Hi allFrom the definition I read "If a binary decoder receives n inputs (usually grouped as a single Binary or Boolean number) it activates one and only one of its 2^n outputs based on that input with all other outputs deactivated".https://www.electronics-tutorials.ws/combination/comb_5.htmlThen I looked at the 7 segments display decoder schematic and I got confused since it looks to me that more than one output is active. Why is it called a decoder then?https://www.electronics-tutorials.ws/combination/comb_6.htmlDo I miss something?Thanks

author: rstofer
author_rank: Super Contributor
timestamp: October 19, 2020, 02:02:02 pm
content: A binary decoder and a 7 segment decoder are entirely different animals. Don't let the word 'decoder' confuse things. I'm sure there are other types of decoders but I haven't had my coffee yet.

author: Peabody
author_rank: Super Contributor
timestamp: October 19, 2020, 02:39:36 pm
content: Something like the 74HC138 is a normal decoder, which turns on only one output depending on the value of the input bits. But a 7-segment decoder turns on the segments that need to light up to display the character. They are completely different in function, but are all decoders in that they provide a specific output that depends on the value of the input.

author: David Hess
author_rank: Super Contributor
timestamp: October 19, 2020, 10:05:51 pm
content: Quote from: Lucky-Luka on October 19, 2020, 10:29:41 amThat is the difference between a 7 segment decoder and a 1-of-X decoder.
7 x 21 dot matrix led display? - Page 1
Forum section: electronics / beginners

author: ambi
author_rank: Newbie
timestamp: June 09, 2015, 08:56:17 am
content: Hi geniusi need an help for designing the small 7 x 21 dot matrix smd LED display with message running display for my certain application ..Can anyone help me out by attaching any simple schematic circuits for my project??Thanks

author: codeboy2k
author_rank: Super Contributor
timestamp: June 09, 2015, 09:23:36 am
content: If you don't know where to begin with a simple 7x21 matrix of LED's, then you should not be building it.Here's a 7x21 LED display with programmable messages:https://store.qkits.com/moreinfo.cfm/MML4Whatever your application is, if you just need a message display then this will get you one for only $20.00.That's much cheaper than a month of design, debug and testing that you might need to do if you are unsureof how to do this.
700 MHz 10 MΩ // 10 pF passive probe - what's the point at all? - Page 1
Forum section: electronics / beginners

author: niconiconi
author_rank: Frequent Contributor
timestamp: May 19, 2021, 06:09:30 am
content: I don't understand a basic question. What are the applications of a standard passive probe with high bandwidth? Everyone knows that a 10:1 probe has significant capacitive loading problems (*) on high frequency signals, but Keysight sells even a 10 MΩ + 9.5 pF probe (N2894A) with 700 MHz bandwidth. A 9.5 pF capacitor at 700 MHz is just -j24 Ω, why would you use it?I guess the only acceptable use is when the source impedance is very low. For example, I can imagine if you probe a CMOS chip output connected to nothing or only to one input, the total 10-20pF probe load is similar to the normal working condition of the chip, and you can probably trust the measurement to an extent. But really, how common the situation is? Does anyone have experience on doing real measurements with a high bandwidth, high capacitance passive probe?(*) Not including low-resistance 10:1 transmission line probes, of course. Just in case that anyone starts nitpicking...

author: PartialDischarge
author_rank: Super Contributor
timestamp: May 19, 2021, 06:27:54 am
content: Clearly a FET probe would be more useful even in that situation that you describe, except for the dynamic range for example needed in gate measurements. At 25Ohm source, 9.5pF gives a maximum of 670MHz, so yes source impedance really lowers the BW.I guess this is just another probe choice and the user must be aware of its limitations

author: tggzzz
author_rank: Super Contributor
timestamp: May 19, 2021, 08:28:30 am
content: Yours is a perceptive and useful question that many apparently experienced people don'tthinkabout. Hence it doesn't really belong in the beginners sectionBasically you are correct; it isn't a useful probe. Not only for the reason you give, but also when you consider the resonance and ringing caused by the tip capacitance and the ground lead inductance.At these frequencies the cheapest effective probe is a resistive divider low impedance Z0 probe. Bonus: it is about the only type of probe that it is reasonable to consider making yourself.

author: radiolistener
author_rank: Super Contributor
timestamp: May 19, 2021, 10:05:07 am
content: Quote from: niconiconi on May 19, 2021, 06:09:30 amMay be there is some rare use case when such probe can be useful.

author: David Hess
author_rank: Super Contributor
timestamp: May 19, 2021, 11:17:41 am
content: Quote from: niconiconi on May 19, 2021, 06:09:30 amPassive probes are relatively inexpensive, have good overload recovery, and are robust compared to active probes.QuoteProbe bandwidth is specified with a 25 ohm source impedance which is not far from the conditions of high speed logic.
70V AC output between 2 grounds. - Page 1
Forum section: electronics / beginners

author: D4no0
author_rank: Contributor
timestamp: July 03, 2020, 08:34:56 am
content: I have a pcb that converts USB to RS232, it is using a CH340G and a MAX2323. The output when not connected works as expected.I try to connect it to a separate device that has its own power supply. When I measure the grounds of connected USB and the device, it reads 70V AC 50Hz.When I try to connect the grounds, the chips start to heat up as a short circuit. I can't understand why this happens, can someone help me solve this?

author: AVGresponding
author_rank: Super Contributor
timestamp: July 05, 2020, 09:08:05 am
content: Does your DUT have a cheap capacitive dropper PSU in it, with maybe a two pin connector to the mains?

author: D4no0
author_rank: Contributor
timestamp: July 05, 2020, 11:45:10 am
content: Ok it seems the MAX2323 chip was fried, after replacing it everything works as expected.

author: wizard69
author_rank: Super Contributor
timestamp: July 05, 2020, 11:13:06 pm
content: Quote from: D4no0 on July 05, 2020, 11:45:10 amIf you have the same voltage differential on the grounds the new device could be at risk of failing. When you have hat much of an offset between ground potentials you likely have serious issues with the building wiring. Properly resolving that may take an electrician and some major work to the buildings electrical system.Other things to consider: measuring with an high impedance meter might give yo misleading voltage measurements. Sometimes optical or other isolation methods need to be used.

author: amyk
author_rank: Super Contributor
timestamp: July 05, 2020, 11:41:13 pm
content: http://www.aplomb.nl/SMPS_leakage/Doc_ie.htmlSome leakage current is normal. How much is there?
741 non-inverting showing DC output - Page 1
Forum section: electronics / beginners

author: blinky87
author_rank: Newbie
timestamp: October 13, 2019, 11:42:04 am
content: Hi allPlaying around with a 741 Inverting opamp with this configuration;input voltage; 0.5VRf = 2.1kRin = 1kV+ = 9vV- = 0and the circuit works.However, in a non-inverting configuration, below, I have the following output;(I have tried different 741's)

author: Andy Watson
author_rank: Super Contributor
timestamp: October 13, 2019, 12:13:52 pm
content: The datasheet suggests that the common-mode input range of the 741 is two to three volts less that your power supply rails. In your case this would be between 2 and 7 volts (at best!). Having one input at 0.5V is not going to work - the 741 is not in its operating range. Similar restrictions apply to the output too.

author: MarkF
author_rank: Super Contributor
timestamp: October 13, 2019, 12:15:45 pm
content: +1 what Andy said. The signal inputs and output can not approach the power rails.Offset Null:

author: blinky87
author_rank: Newbie
timestamp: October 13, 2019, 12:30:47 pm
content: Thank you guys. A lot of help here!

author: blinky87
author_rank: Newbie
timestamp: October 13, 2019, 01:32:39 pm
content: I got the circuit working, thank you guys. Seeing the clamping in the video helped and confirmed my thoughts as well as your help.Also since it was single supply VCC+ 9V and VCC- was 0, clearly I had huge clamping and looked like half wave rectification.Putting VCC+/- 9 worked.
74AC14N  - Difference if made in 1995 or 2017? - Page 1
Forum section: electronics / beginners

author: K1JOS
author_rank: Regular Contributor
timestamp: August 30, 2017, 01:41:15 am
content: Looking at current descriptions of this Schmitt trigger input hex inverter - it makes a big deal about jitter free outputs while the datasheet for the same part, same manufacturer, bought back in the early 1990's makes no mention of jitter. Are same part number, same manufacturer made 25 years ago identical in performance to modern manufactured components?jerry

author: Messtechniker
author_rank: Frequent Contributor
timestamp: August 30, 2017, 06:39:57 am
content: Probably not because of changed innards.If you have the two samples, visit your dentistfor Xraying. You will then see.I have heard that some logic IC series are to day based on FPGAsprogrammed for the respective function. Can anyone confirm this?

author: Jeroen3
author_rank: Super Contributor
timestamp: August 30, 2017, 07:22:24 am
content: They will have switched fab and process several times, so the thresholds will differ.

author: Zero999
author_rank: Super Contributor
timestamp: August 30, 2017, 07:38:39 am
content: Quote from: K1JOS on August 30, 2017, 01:41:15 amThe die might be smaller, but other than that, it will be the same.Quote from: Messtechniker on August 30, 2017, 06:39:57 amI very much doubt that. There's more chance of it being a mask programmable logic array, but I doubt they'd use a more expensive process, when a cheaper one will do. Anyway, how many FPGAs are rated for 2V to 6V operation like the 74AC14 is?
74HC04 vs 74VHC04 hex inverter -- difference? - Page 1
Forum section: electronics / beginners

author: 13hm13
author_rank: Frequent Contributor
timestamp: May 12, 2020, 03:56:05 pm
content: Probably a v. simple question for many of you but what is the difference between 74HC04 vs 74VHC04 hex inverter. What's the "V" for ?Also, what are your thoughts about the Potato Semi manuf of chips (get it: Potato chips!):http://www.potatosemi.com/Their semis seem to be popular in the DIY audio and audiophile community.

author: AVGresponding
author_rank: Super Contributor
timestamp: May 12, 2020, 04:00:50 pm
content: V is for "very" as in "Very High speed Cmos". 3ns gate delay time vs 12ns for HC.
74HC123 5-10ms Pulse on Edge - Page 1
Forum section: electronics / beginners

author: ripper121
author_rank: Contributor
timestamp: November 28, 2016, 06:55:08 pm
content: Hello:),i have a Reed Contact which can be open or closed,on each change (Open to Close or Close to Open) Ineed a 5-10ms Pulse (HIGH-LOW-HIGH).With 2uF and 10kOhm on CEXT and REXT i get about 6.75ms Pulse. (i used Page 10 Table 7 to calculate that).On page 5 table 3 are the states.http://www.nxp.com/documents/data_sheet/74HC_HCT123.pdfIs my schematic and calculation correct?Is it with this schematic possible?

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: November 29, 2016, 07:21:20 am
content: Looks like you're in the ballpark.http://www.ti.com/lit/an/scla014/scla014.pdfConsider using a smaller C and larger R. The discharge current will be smaller, and hence the likelihood of that current causing ground bounce.

author: ripper121
author_rank: Contributor
timestamp: November 29, 2016, 07:24:06 am
content: Thank you for this info.Can you say something about my schematic, will it work?Because there are some undefined states (not in the table)
74HC4051 Why have a VEE / Negative supply Connection? - Page 1
Forum section: electronics / beginners

author: jwhitmore
author_rank: Regular Contributor
timestamp: September 01, 2020, 12:31:55 pm
content: The title might alternatively be "Why did that work?". I wanted to switch my electric guitar about with a uC and decided I'd try the 74HC4051 . So I bread boarded a simple circuit. The chip has both VCC, Gnd and VEE connections, but to keep it simple I connected VEE to Ground just as a simple test, with a single +5V rail. My first test was to just measure resistances between pins and check that I was switching correctly. That worked, so I decided that I'd connect up my signal generator and try to switch a sine wave through the chip. As I've got VEE connected to ground I assumed that it would not fully work, but might as well test that it half works. I expected the sine wave to be cut off when it went negative, but it fully worked, both the positive portion of the sine and the negative?Maybe I should just accept that it works and I don't need a negative supply rail connected, but obviously I have misunderstood something. I went through the datasheet again  but I'm missing something in all the electronic specifications. I'm sure the manufacturer wouldn't add a negative supply pin if it wasn't needed? So do I need a negative supply rail.? I'm left scratching my head.https://assets.nexperia.com/documents/data-sheet/74HC_HCT4051.pdf

author: MasterT
author_rank: Frequent Contributor
timestamp: September 01, 2020, 12:47:31 pm
content: Check page 22, distortion. Otherwise it would be o'k on single +5 power, assuming biasing input with 2 resistor (forming 2.5V voltage) and applying signal from SG via Capacitor.

author: TimFox
author_rank: Super Contributor
timestamp: September 01, 2020, 01:34:20 pm
content: The "ground" pin is actually an input, being the reference voltage for logic low on the switching input. The actual switches, level shifter, and switch driver operate between the positive and negative voltages, so that a ground-referenced logic input can switch an analog signal that goes both sides of ground, up to the levels specified in the datasheet.
74HC4052 as a serial extension?  - Page 1
Forum section: electronics / beginners

author: abdullahseba
author_rank: Frequent Contributor
timestamp: June 28, 2017, 02:23:58 pm
content: HiCan I use a 74HC4052 as "extension lead"?I have 2 serial devices that have an LCD and when connected to the serial port I need both to display the same thing. It also has a keypad and both need to send to the same port.Its unlikely that both units will be used at the same time an even more unlikely that a button on each keypad will be pressed at exactly the same time.I thought that muxes where used to more as a "switch" than a "hub" in networking terms but this sparkfun schematic seems to be what I wanthttps://www.sparkfun.com/datasheets/Components/General/SerialMux-v10.pdfDoes this do what I want? Or is it a switch?Thanks in advance.

author: alm
author_rank: Super Contributor
timestamp: June 28, 2017, 02:58:43 pm
content: It will be a switch in that the UART on your microcontroller (?) will only be transmitting to and receiving from one of the serial devices at the same time. The difference to a switch in network terms is that the microcontroller will have to explicitly switch between the displays. So you have to change the MUX configuration (through the MUX_A/MUX_B lines) to select which display you want to talk to. Similar to the old manual KVM-switches where you had to press a button or turn a dial to select a computer.

author: abdullahseba
author_rank: Frequent Contributor
timestamp: June 28, 2017, 03:25:42 pm
content: SoQuote from: alm on June 28, 2017, 02:58:43 pmSo how do you switch between the devices in the circuit? I seen no other inputs to the micro in the schematic.

author: alm
author_rank: Super Contributor
timestamp: June 28, 2017, 05:19:32 pm
content: You would connect one of the GPIOs to MUX_A or MUX_B. Two GPIOs if you want to control three or four devices. See the 74HC4052 datasheet for how the A and B pins relate to the 0/1/2/3 outputs. Whichever pin you do not connect to your micro will be pulled low by the 1 kOhm resistor, so connecting one of the inputs if sufficient if you only need to switch between two outputs.
74HC595 and slow programming languages (PHP) - Page 1
Forum section: electronics / beginners

author: laxamar
author_rank: Contributor
timestamp: September 09, 2022, 06:30:12 pm
content: I sometimes stumble into WebMD and find that I have all sorts of diseases ...Same thing happens when I read stuff on other sites and I think everything is going to break ...Long Story Short, I read somewhere (I'll find it if necessary) that I can't use too slow of a clock on HC circuits (specifically 74HC595) as it might leave the internal shift registers in unstable states, they are designed for high speed.I am using PHP and my application is very low speed, I need to use low power (3.3V) so I've been sticking with 74HCxxx components. I am building a breadboard with 74HC595 DIP parts to test things out. I'm just now paranoid that on my final SMD project , on a busy PI4 CPU (graphics and network invovled), my clock triggers in PHP might become too slow for the chips and have unexpected results. It's *probably* paranoia, as 32 bit to 64 bit shifts before storing should be fast enough, but I though I might ask anyway.Should I be worried about the performance of the PHP 8 engine for outputting GPIO signals (2 clocks, one serial data) fast enough for High Speed CMOS parts?

author: dmills
author_rank: Super Contributor
timestamp: September 09, 2022, 06:41:08 pm
content: It is not the speed of the clock that matters, it is the rise and fall time of the edge, and that is a circuit thing not a software one (In most cases).The concern is that a clock with a sufficiently slow rise time may hang around whatever the threshold voltage is and give rise to an extra clock pulse due to noise taking it across the threshold, but that is about circuit design and board layout, not how slowly your program executes.If working in something actually fast, like say assembler or maybe C you can manufacture some 'too fast' things like failing to meet hold time constraints, but you are not going to get close to that in PHP!

author: RoGeorge
author_rank: Super Contributor
timestamp: September 09, 2022, 06:48:19 pm
content: Quote from: laxamar on September 09, 2022, 06:30:12 pmNo. It'll work just fine, because any GPIO has fast enough edges. No worries whatsoever, not even if you pulse that 74HC595 only once a year.

author: laxamar
author_rank: Contributor
timestamp: September 10, 2022, 12:28:35 am
content: Quote from: dmills on September 09, 2022, 06:41:08 pmAhhh, that makes much more sense. That's a GPIO thing. Phew I can sleep well tonight, as soon as I figure out from WebMD why my eyes are red .....

author: dmills
author_rank: Super Contributor
timestamp: September 10, 2022, 11:09:35 am
content: WebMD, the hypochondriacs friend...
74HC595 connect to Vcc - Page 1
Forum section: electronics / beginners

author: shobo
author_rank: Regular Contributor
timestamp: December 17, 2017, 05:36:29 pm
content: Why is the SCL line on a 74HC595 connected to Vcc (i guess the more correct terms would be pulled high)?i took inspiration from this instructable:http://www.instructables.com/id/Arduino-powered-7-seg-LED-display-using-Shift-Regi/to design a display board for a soldering station i intend to build somewhere in the future.

author: rstofer
author_rank: Super Contributor
timestamp: December 17, 2017, 06:05:30 pm
content: Because a) signals can't be allowed to float and b) the signal is active low and it shouldn't be active. I would never tie a pin directly to Vcc instead I would use a 1k resistor. Opinions vary on this but I have never liked tying signals to a solid Vcc.

author: David Hess
author_rank: Super Contributor
timestamp: December 17, 2017, 07:07:33 pm
content: Quote from: rstofer on December 17, 2017, 06:05:30 pmTying a logic input to Vcc matters where TTL (transistor transistor logic) that uses emitter inputs is used. The input transistor will conduct current in reverse mode limited only by reverse beta and input resistance. Later TTL families use diode inputs which do not suffer from this problem.This is not a problem for HC or any CMOS logic.

author: 2N3055
author_rank: Super Contributor
timestamp: December 17, 2017, 07:13:31 pm
content: That pin is Shift Register Clear. It resets contents of shift register. It is active low. If you don't want to use reset, tie it to logic high and ignore it.Regards,Sinisa

author: rstofer
author_rank: Super Contributor
timestamp: December 17, 2017, 10:07:35 pm
content: Quote from: David Hess on December 17, 2017, 07:07:33 pmI'm just old school, I guess. However, if I build a PCB and connect the pin to the Vcc plane (inside a 4 layer board), I can never change my mind (short of cutting off the pin). OTOH, if I connect the pin to Vcc through an SMD resistor, I can add a bodge wire and regain control of the signal. I can choose to keep or remove the resistor.You're right, this admonition goes back to the early days of TTL.

author: 2N3055
author_rank: Super Contributor
timestamp: December 17, 2017, 10:30:42 pm
content: Quote from: rstofer on December 17, 2017, 10:07:35 pmNah, that's just smart... I do that or at least run a short trace before diving into layers.. So I have something to cut in case I need it....Regards,Sinisa
74HC595 Qh' floater - Page 1
Forum section: electronics / beginners

author: PerranOak
author_rank: Frequent Contributor
timestamp: June 26, 2021, 04:49:59 pm
content: I am creating a PCB involving a 74HC595. I don't really get the function of Qh' - it seems to be the inverse of Qh but ahead of it.Anyway, I'm not using Qh' (obviously!) so I wondered if it should be left floating or should I use a pull-up/pull-down. It is an output so I don't know.Cheers.

author: oPossum
author_rank: Super Contributor
timestamp: June 26, 2021, 04:52:18 pm
content: It is before the output latch and is used to cascade shift registers. It is an output so there is no need to connect anything to it.

author: mrkev
author_rank: Regular Contributor
timestamp: June 27, 2021, 01:37:12 pm
content: This allows you to chain multiple shift registers together. Just use Qh' of the first register as input of another, connect all driving signals of both devices and you have a 16b register. This was very handy back in the day, when uC were really expensive and you didn't have enough logic outputs. Now it's mostly used when you wanna drive some slow signalization (f.e. panel of LEDs).

author: PerranOak
author_rank: Frequent Contributor
timestamp: June 27, 2021, 02:12:44 pm
content: Cheers both.BTW does it need a 100nF cap between Vcc and ground?

author: Siwastaja
author_rank: Super Contributor
timestamp: June 27, 2021, 02:22:36 pm
content: Quote from: PerranOak on June 27, 2021, 02:12:44 pmVery highly recommended unless you have knowledge or measurements to prove doing otherwise works out.
74HC595 weirdness - Page 1
Forum section: electronics / beginners

author: konzill
author_rank: Newbie
timestamp: October 13, 2019, 11:27:33 pm
content: Edit: looks like I have a couple of bad chips, either broken or just dodgy. I replaced them with another one bought at a different store on a different day and the circuit works right.Hi. I've been learning how to wire up this shift register. Specifically I'm using the Texas Instruments SN74HC595.But I've had some weird behavior. The circuit had no output until I added pull up resistors to +5v on the output pins of the chip. As soon as I added these my LED array, also wired to the output, started producing the expected output. The thing is that none of the tutorials for how to wire up this circuit seem to need to do this. I've now built the circuit from scratch using new components twice and they both behave this way.the circuit on each output pin looks like this:Code:chip output------- LED ---- R1 --- Gnd|R2 --- +5vEDIT: I've attached a photo of my actual breadboard. Seeing as its been asked I have OE low and MR high in this setup.The Arduino code is set up to count from 0 to 255. And with the R2 resistors in place I'm seeing the green LED's count up exactly as I would expect.

author: amspire
author_rank: Super Contributor
timestamp: October 13, 2019, 11:42:51 pm
content: The IC should be able to put a few mA through a led without a pull-up. How much voltage is across the LED when it is on? If you have a LED that needs a particularly high voltage or more then 1 LED in series, that could be the problem.Do you have the OE pin connected to 0V?Richard

author: wraper
author_rank: Unknown
timestamp: October 13, 2019, 11:49:22 pm
content: SN74HC595 has 3-State Output. What you say means that IC output is in high-Z state, not logic high.

author: konzill
author_rank: Newbie
timestamp: October 14, 2019, 12:45:43 am
content: So does that mean things are working correctly? Or that I need to change one of the other inputs for things to be working correctly? Do I need to change my output enable? The pin Is currently pulled low.

author: thinkfat
author_rank: Unknown
timestamp: October 14, 2019, 04:31:02 am
content: OE low is fine, but remember to also pull MR high.
74HCT125 quad driver as cheap 100mA push/pull driver - Page 1
Forum section: electronics / beginners

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: June 25, 2013, 07:17:08 pm
content: Instead of using the relatively expensive (~5€) Microchip TC4468 as quad push/pull driver in one of my projects I thought about replacing it with 4 cheap 74HCT125 quad drivers, where I use 4 outputs in parallel on each 74HCT125 to get 100mA combined. This would reduce the cost to <1€ for the four 100mA/50Ohm outputs. I'll add Polyfuses and 5V Transil suppressor diodes as overvoltage protection.So is this a bad idea for a low cost 100mA (MOSFET) push/pull driver? Are there maybe more elegant solutions?

author: bingo600
author_rank: Super Contributor
timestamp: June 25, 2013, 07:23:22 pm
content: Do you need the tristate ?Else a HCT14 has 6 outputsOften used as 1 package as driver for the other 5 , and then as a bonus it's not inverting the output./Bingo

author: edavid
author_rank: Super Contributor
timestamp: June 25, 2013, 07:33:22 pm
content: Look again, most vendors have a maximum supply pin rating of 50-70mA for a 74HCT125. Exceeding this can cause latchup.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: June 25, 2013, 07:39:36 pm
content: Quote from: edavid on June 25, 2013, 07:33:22 pmGood point. Have to check that.@bingo600I don't need the tristate urgently, but it is sure nice to have.Also I could use the 74HCT365 if I wanted a hex driver. This way I'd need only 3 instead of four ICs to get the 4 channels with 100mA each. However, the 74HCT365 has a 500 mW power limitation, so I couldn't use all 6 outputs without exceeding that.Same is true for the 74HCT14 unfortunately.

author: SeanB
author_rank: Super Contributor
timestamp: June 25, 2013, 07:44:31 pm
content: Use an octal bus buffer, then you can get 2 drivers out of each chip.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: June 25, 2013, 07:47:59 pm
content: Yeah, but I'm not so optimistic to find one that could really deliver 200mA without dying of heat. Letting aside that latch-up issue.

author: MasterOfNone
author_rank: Regular Contributor
timestamp: June 25, 2013, 08:34:32 pm
content: I’ve never tried doing anything like that, and I must admit I was thinking that if one of the drivers in the package is slightly slower than the others, then it could still be pulling its output low while the others start pulling their output high. But if the outputs are connected in parallel, this would temporarily short the Power Supply. But in reality the transition time of the devices isn’t zero so it’s unlikely that you would get a full short if this was the case anyway.

author: TerminalJack505
author_rank: Super Contributor
timestamp: June 25, 2013, 08:36:37 pm
content: You might also check out the drivers for the other logic families. The 74ACxx, 74ACTxx and 74Fxx-series buffers/drivers can usually source/sink more current than the 74HCxx/74HCTxx equivalent part. They can be a bit more finicky, however.
74ls593 high VoL ? - Page 1
Forum section: electronics / beginners

author: bitman
author_rank: Unknown
timestamp: November 02, 2017, 12:39:45 am
content: Can someone help me understand if what I'm observing is lining up with the data sheet? I have a few 74LS593s and while it works great, the output voltage I'm seeing when the chip is "disabling output" (CCKEN high), G and !G are both LOW I see about 1.5->1.7 volts on the outputs (Q lines). If I read the datasheet right I should only be expecting around 0.4volts? I realize this isn't tri-state so I'm probably asking for problems as I connected it straight to the bus which is causing issues (other chips that aren't tri-state seems to do the same).So I'm confused in regards to "facts vs. datasheet" here:http://pdf1.alldatasheet.com/datasheet-pdf/view/28020/TI/SN74LS593N.htmlJust to be sure I took a picture of the chip just in case I've got the wrong data sheet.

author: Ian.M
author_rank: Super Contributor
timestamp: November 02, 2017, 12:48:30 am
content: Page 2 top left shows that the I/O lines in input mode look like a 25K pullup to Vdd clamped at about 1.5V with a Schottky diode so they can only source current. If you want a true tristate, use CMOS logic not the bipolar TTL families, but beware of input threshold differences degrading noise margins in a mixed system and cross-family fanout limits.

author: bitman
author_rank: Unknown
timestamp: November 02, 2017, 01:05:48 am
content: Quote from: Ian.M on November 02, 2017, 12:48:30 amThe title I found claims tri-state, and "typical of Q outputs" looks very much like a traditional tri-state setup? Anyway, I'm still struggling with why the sheet later states 0.4 volt - but I guess that's when there's an active low signal on the line. In this case there's no active signal.I guess I need to figure out a better mechanism connecting this counter (PC) to a bus. Thanks for very fast feedback!

author: Ian.M
author_rank: Super Contributor
timestamp: November 02, 2017, 01:13:00 am
content: It should be noted that an bipolar TTL output only tristate buffer wouldn't have the same issue. Its only bidirectional ones that have the input circuit acting as a weak pullup to an intermediate voltage.

author: bitman
author_rank: Unknown
timestamp: November 02, 2017, 01:37:28 am
content: So I changed my pulldown resistor on the "bus" from 1K to 470- and now the lines all dropped to way below 1v (approx 400mv). That fixes my problem, but now I need to figure out WHY that fixed it. It's fun learning - but at times it's frustrating too.Thanks again @Ian.M for a quick response.
74LVC series above 3.6V Vcc ? - Page 1
Forum section: electronics / beginners

author: westfw
author_rank: Super Contributor
timestamp: June 12, 2017, 06:34:48 am
content: The 74LVC series is supposed to be 3.6V logic with 5V tolerant inputs. But the datasheets say that the max supply voltage is 6.5V !Can I use some 74LVC00s in a 5V system if I'm missing more appropriate logic families? What can I expect, behavior-wise, from the high (but not too excessive) supply voltage?

author: bson
author_rank: Unknown
timestamp: June 12, 2017, 08:10:12 pm
content: What mr blue said above. LVC is also varies in its tolerance and it varies between parts, so you'll need to check the specific datasheets on this one.

author: Zero999
author_rank: Super Contributor
timestamp: June 12, 2017, 10:21:44 pm
content: So the part is specified to work up to 3.6V but the absolute maximum voltage rating is 6.5V. . .This means the part is guaranteed to work at 3.6V and no more. It will tolerate voltages up to 6.5V but without any guarantee it'll still conform to the other specifications such as power consumption.

author: Cervisia
author_rank: Regular Contributor
timestamp: June 13, 2017, 12:27:15 pm
content: Please note that the single-gate LVC devices (74LVC1G00 etc.) are guaranteed to work at 5 V.I suspect that it would be possible to use a single gate in a larger chip at 5 V, but that using multiple gates that switch at the same time would result in ground bounce large enough that the entire chip might no longer work in the worst circumstances.
74xx IC, 5V logic - Page 1
Forum section: electronics / beginners

author: IvoS
author_rank: Frequent Contributor
timestamp: February 16, 2014, 05:09:14 pm
content: I am designing circuit with 74AC74, 74AC00, 74AC14 and CD4015 which can be powered with 2-18V but will run on 5V as well. My question is how to connect SET and RESET pins, if via a resistor or straight to Vcc or Gnd. What to do with 74AC14 unused invertor inputs, HI or LOW? Thanks.

author: grumpydoc
author_rank: Super Contributor
timestamp: February 16, 2014, 05:14:36 pm
content: 74xx74 SET and RESET inputs need tying to VccDo you really need "AC" BTW

author: IvoS
author_rank: Frequent Contributor
timestamp: February 16, 2014, 05:31:15 pm
content: I don't really need fast AC type, but I already have them so I'll use them. Should I connect them through a resistor or straight to Vcc.?

author: grumpydoc
author_rank: Super Contributor
timestamp: February 16, 2014, 06:00:23 pm
content: I usually go via a 10k resistor but TBH it's probably not needed.My understanding is that AC can be a bit tricky because of the fast edges. At the very least make sure everything is well decoupled.