hybridfree/eevblog-posts huggingface dataset:
Delete Delete Delete - Page 1
Forum section: electronics / beginners

author: The_Almighty_Bacon_Lord
author_rank: Contributor
timestamp: May 15, 2016, 04:14:27 pm
content: Delete Delete Delete

author: madires
author_rank: Super Contributor
timestamp: May 15, 2016, 04:32:45 pm
content: I see, the AO8810 is the MOSFET used on the protection board. The maximum voltage for that MOSFET is V_DS, i.e. 20V. But that doesn't matter much because the protection board is just that, a protection board, not a charge controller. If you wan't to charge the battery properly you should use a charge controller. There are plenty of chips for that or cheap ready-to-use modules on ebay (search for "LiPo charger module").

author: Audioguru
author_rank: Super Contributor
timestamp: May 15, 2016, 04:44:09 pm
content: The protection board disconnects the battery if your charger malfunctions and tries to charge to a voltage too high or if your load tries to discharge the battery to a voltage too low. It has sensors and a Mosfet switch. The switch is either ON so it does not get hot or it is OFF so it does not get hot. A charger is linear not a switch so it gets hot and needs cooling with a heatsink.Since ebay sells cheap Chinese "stuff" and knows nothing about Chinese or electronics then you must guess what else the protection board does.

author: rstofer
author_rank: Super Contributor
timestamp: May 15, 2016, 09:43:16 pm
content: Well, the replies kind of answer your question. The board isn't a charger, it only protects the battery from over/under voltage and overcurrent at the voltages and current specified. If you want to charge a battery, you need a battery charger. It may already include the features of the protection board, or not.If you need the charging specs for a battery, best research that bit first. The protection board is only working like a resettable fuse.Whether it is applicable to "your" battery is another question. What are the specs for the battery?Why don't you just buy a battery charger?By itself, this device doesn't discharge the battery either. At least I can't see where/why it would.It serves only to protect the battery from damage.

author: Monadnock
author_rank: Contributor
timestamp: May 15, 2016, 09:53:09 pm
content: Looks like the IC is this one:http://datasheet.sii-ic.com/en/battery_protection/S8261_E.pdfMaximum recommended input voltage is 8V.This part is designed to be fed by a LiPo charger. I wouldn't hook up a CV power supply to it.

author: madires
author_rank: Super Contributor
timestamp: May 16, 2016, 09:55:06 am
content: Quote from: The_Almighty_Bacon_Lord on May 15, 2016, 09:21:42 pmPlease readhttp://batteryuniversity.com/learn/article/charging_lithium_ion_batteriesand watch
Noobie question re: Switching USB devices - Page 1
Forum section: electronics / beginners

author: medical-nerd
author_rank: Regular Contributor
timestamp: February 06, 2018, 07:20:53 pm
content: HiyaI have 4 rtl-sdr v3 dongles that I am going to connect to an industrial 4 port hub that takes a separate power supply, all of which will be enclosed in a 1u rackmount case - with low noise power supply,cooling, ferrite loaded USB cables etc, etc.Now for the newbie question - I want to be able to turn each dongle on/off as required. As I understand it - the USB A male connector has the power pins longer than data pins so that power is connected first, and data pins will not be overloaded by trying to supply power.Is this always true? Does this mean that I can't leave the dongle connected and just switch the vcc line? Do I have to use a 4PST switch for each dongle?Cheers

author: Bear207
author_rank: Contributor
timestamp: February 22, 2018, 12:21:15 am
content: Quote from: medical-nerd on February 06, 2018, 07:20:53 pmGreetings,This question about USB power handling is going impact a project I'm going to be working on in the near future.Sure hope someone here is able to provide some info or direction where we might find some insight.Regards

author: ez24
author_rank: Super Contributor
timestamp: February 22, 2018, 12:50:11 am
content: I want to see what the experts say, but I bet a SPST will work.

author: ovnr
author_rank: Frequent Contributor
timestamp: February 22, 2018, 01:12:09 am
content: OPre-posted thisin a different sub-forum which did get replies.

author: Bear207
author_rank: Contributor
timestamp: February 24, 2018, 07:45:43 pm
content: Quote from: ovnr on February 22, 2018, 01:12:09 amThanks for the redirect ovnr.Sent from my Pixel XL using Tapatalk
NOR latch in an envelope gen circuit not working - Page 1
Forum section: electronics / beginners

author: belzrebuth
author_rank: Frequent Contributor
timestamp: February 23, 2022, 10:02:37 am
content: Hi all,I'm trying to repair a synthesizer that features a slight variation of the "Barry Klein envelope generator" as shown in the attached schematic.The problem as I understand it is the NOR SR latch which is not working at all for some reason..When I trigger the rest of the envelope with a fast gate signal I get it to perform but I see no activity coming out of the SR latch with a gate signal applied.I tried to replicate the circuit in a breadboard only to get the same behavior.In my case the circuit is powered with a 12V so to get the 10V at the comparator input the 47k is 22k.Also there is a 2.2k resistor in series with the potentiometers (which BTW are 1M not 5MΩ) to prevent possible unwanted lockups of the latch.I'm puzzled to why this textbook circuit does not work at all..I tried a tad bigger capacitors in the nor input to make the trigger pulse wider to no avail.

author: Terry Bites
author_rank: Super Contributor
timestamp: February 23, 2022, 10:24:05 am
content: Dont malign the Klein. Which one of his many circuits are you referring to?Bad IC?Bad wiring?Logic impropperly driven? Wrong Vdd?Not using 4000 series logic? Unused inputs flapping about?What Nor are you using- show your circuit or i'll have to read your mind and tell your Mum what I found in there.

author: belzrebuth
author_rank: Frequent Contributor
timestamp: February 23, 2022, 11:10:31 am
content: I know this circuit should work that's why I'm puzzled.Nothing against Klein of course!In the breadboard I needed to swap the upper NOR capacitor with a 100nF one in order to work.What I'm trying to repair is an orgone systems enigiser synth so no schematics avalaible.I just found the fault though..There was a 1k resistor after the 1nF capacitor where the gate signal connects.The other end of this resistor goes to the input of the other NOR gate.(again after the 1nF cap)I don't know why a resistor would be there but replacing it with a 2k pot and messing with it a bit fixed it.Cutting the 1k resistor entirely results in the SR latch sticking HIGH.

author: RoGeorge
author_rank: Super Contributor
timestamp: February 23, 2022, 11:17:52 am
content: Quote from: belzrebuth on February 23, 2022, 10:02:37 amI don't see any attachments.
Nordmende FG-387 TV signal Generator - Page 1
Forum section: electronics / beginners

author: crt_cowboy
author_rank: Regular Contributor
timestamp: February 01, 2022, 03:34:21 pm
content: Hi,I found a Nordmende FG-387 (https://www.radiomuseum.org/r/nordmende_farbbalkengenerator_fg387.html)The device has two outputs: one with 75ohms and the other one 60hm.My understanding is that 75ohm is video composite and 60ohm RF modulated. Is that correct ?Also the device outputs H-SYNC 15KHz. What is it for? In what kind of troubleshooting on TV set was this used for ?Any advice would be appreciated.

author: Renate
author_rank: Super Contributor
timestamp: February 02, 2022, 07:11:37 pm
content: That's a pretty looking unit. It would be used for troubleshooting both monitors (with a normal studio 1V P-P 75Ω signal) and TVs (with a modulated RF signal). The H sync output gives you something to sync your 'scope to. You can easily see how/if the horizontal oscillator in your DUT (device under test) is locking up.Why/how 60Ω was ever a standard is another question. In the US during that time it was mostly 300Ω (balanced) "twinlead" or else 75Ω "cable TV".

author: crt_cowboy
author_rank: Regular Contributor
timestamp: February 04, 2022, 05:31:15 am
content: Thanks for the reply. Indeed putting the scope on the 75ohm output confirmed it outputs video signal.Just out curiosity, why horizontal oscillator and not vertical ? Are there more failures on the horizontal oscillator ?

author: Renate
author_rank: Super Contributor
timestamp: February 04, 2022, 11:02:47 am
content: Yeah, a lot of generators would have both H & V sync available.OTOH, back then a lot of 'scopes had built-in 50/60 Hz AC power sync, so that was good enough to look at your V.Now that I think of it, 60Ω was the old European standard for antenna feeds.

author: crt_cowboy
author_rank: Regular Contributor
timestamp: February 04, 2022, 05:22:37 pm
content: Indeed that's true that 50/60 Hz can be found easily from the AC.

author: decoder_82
author_rank: Regular Contributor
timestamp: February 13, 2022, 05:10:35 am
content: Quote from: crt_cowboy on February 04, 2022, 05:31:15 amSome signals generators like the Philips PM5508 offers both vertical and horizontal sync.
Noritake itron GU140C32F pinout? - Page 1
Forum section: electronics / beginners

author: nardev
author_rank: Unknown
timestamp: November 20, 2020, 04:37:38 am
content: I remember powering this thing up and displaying some text but i forgot the pinout. I'm pretty lost. The official docs either doesn't show it or i have no idea how to read it.Here is the pics of the display and the official docs url:docs:https://www.noritake-elec.com/products/model?part=GU140X32F-7000BArduino Lib:https://www.noritake-elec.com/support/design-resources/support-guide/arduino-code-library-quick-start-guidePlease if you have any clue, help, i have only one i don't want to damage it.

author: ataradov
author_rank: Super Contributor
timestamp: November 20, 2020, 05:03:45 am
content: Full DS is registration-only, but even the brief one shows this :QuoteIt looks like this is a slightly different version as it only has 6 pins, but the last one is NC.Missing wire and red/black for VCC/GND also confirm this pinout.

author: ledtester
author_rank: Super Contributor
timestamp: November 20, 2020, 05:14:50 am
content: On this page:https://www.noritake-elec.com/support/design-resources/support-guide/arduino-code-library-quick-start-guidehave a look at lines 13-20:You should uncomment one of them depending on whether you want serial or parallel communication. The constructor arguments tell you what the pin assignments are, e.g.:GE7000_Serial_SPI interface(MOSI,BUSY,SCK,RESET,CS)orGE7000_Parallel interface(PIN3,BUSY,RESET,WR,RD,D0,D1,D2,D3,D4,D5,D6,D7)

author: nardev
author_rank: Unknown
timestamp: November 20, 2020, 05:17:38 am
content: Quote from: ledtester on November 20, 2020, 05:14:50 amyea but i'm concerned with the order... Order in the code and on the board, don't align...I'm gonna try it now with SPI on esp8266, don't have any arduino now.

author: nardev
author_rank: Unknown
timestamp: November 20, 2020, 05:21:58 am
content: Here is the hardware docs, i couldn't figure out the pinout at first sight..p.s. ups

author: ataradov
author_rank: Super Contributor
timestamp: November 20, 2020, 05:23:46 am
content: Your module only has enough pins for an asynchronous interface described in the section 5.3.2 "Asynchronous serial interface timing" and my pinout applies.This display looks like the one they were giving away for free or super cheap some years ago. I think I have one somewhere in the office too.

author: nardev
author_rank: Unknown
timestamp: November 20, 2020, 05:26:33 am
content: Yes, i think that's how it ended up in my hands years ago.wonderful looking display though, just want to put it in one IOT weekend project.
Normal voltage spikes from computer PSU ? - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: November 24, 2018, 04:56:32 pm
content: I'm just checking a 750W PSU that might or might not have problems. It powers up fine, and starts a little dual core PC. Looking at the outputs tho IDK if it's normal or not.It's switching at ~140kHzSo the 12V rail, I get the inductive ringing of 2.0Vpp max on the 1st ring, 1.25Vpp by the 2nd ring, and by the 6/7 ring it's decayed to next to nothing. Those rings in total span ~600ns, the period of the switching is 7us.The 5V rail looks the same shape/time wise, with the 1st ring max of 1.84Vpp, 1.33Vpp on the 2nd, and drops off by 6-7 rings.The ripple looks fine. I'm just wondering if those inductive spikes sound about normal at 2Vpp ?I could pull the output caps and check ESR. I don't have any proper way to load test these PSUs, this test rig is under well under 300W.

author: David Hess
author_rank: Super Contributor
timestamp: November 24, 2018, 06:50:51 pm
content: How did you make the measurement?It is very easy for common mode switching noise from the power supply to corrupt a single ended measurement where a common ground is used. The ATX specifications require noise measurements to be done differentially.You may be able to verify a problem with common mode noise by connecting the oscilloscope probe tip and ground lead to the spot where the ground lead is connected for the measurement.I would expect 10s to low 100s of millivolts of peak-to-peak noise maximum.

author: lordvader88
author_rank: Frequent Contributor
timestamp: November 24, 2018, 08:17:29 pm
content: I ordered diff. probes, they're in the mail.I'm going to probe my main PSU, see what it looks like.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 24, 2018, 09:20:36 pm
content: That's not going to affect anything attached to it, and as alluded to, it's more likely common mode.I strongly suspect the poor bugger can't pass emissions (up the power cord) though.Tim
Normalized Mean Square Error (NMSE) Calculation - Page 1
Forum section: electronics / beginners

author: tec5c
author_rank: Frequent Contributor
timestamp: September 17, 2015, 09:41:28 am
content: Hi all,This question is from my communication systems subject at Uni. We have not covered this in lectures (nor previous math/stats classes)...I'm quite sure that I'm making a mistake in my working (2.5 pages of working) as my final answer results in 0 for different values of n.The question:Where s(t) isI'm quite sure the denominator in the exponential, for the NMSE, should be T rather than N, to match with s(t)...??An expression for the fourier coefficients, Cn, has previously been found, as well as the average power P.I can provide more of the question + my working if anyone would like to see it (not at home at the moment so will have to post it up later).As I haven't learnt this in class, I have tried to self educate in order to understand exactly what the question is asking. I am quite confident that I do grasp it, though if anyone can explain it then I'm hoping something may click so I realise where I've gone wrong.
Not Contact, Self Powered Mains Detection to a uC - Page 1
Forum section: electronics / beginners

author: Docara
author_rank: Regular Contributor
timestamp: July 03, 2018, 06:15:50 pm
content: HiI'm looking to have a reliable non contact and self powered mains detection to a microcontroller. The distance from the available power cable to the microcontroller is about 4m.The only thing I can think of is a something like a CT transformer with a resistor across its output to give a voltage with a Bridge rectifier and Cap thrown in . The maximum amperage available is 16A and around .5A minimumAny thoughtsMatt

author: C
author_rank: Super Contributor
timestamp: July 03, 2018, 08:22:08 pm
content: CT transformer is measuring current not voltage.You are feeding one wire through center of transformer.#114 No contact mains detector for Arduino & Pi (just 10 components) Ralph S Bacon
Not draining Li-Ion too far - Page 1
Forum section: electronics / beginners

author: MikeK
author_rank: Super Contributor
timestamp: November 10, 2012, 02:19:07 am
content: So I have a Li-Ion battery powering a small project. It's going through an MCP1700 3.3V regulator. The circuit is low-power, but I don't want the battery voltage to drop too far and get damaged. Is there a way to prevent it? Does the little circuit inside the battery prevent it?

author: Psi
author_rank: Super Contributor
timestamp: November 10, 2012, 02:27:08 am
content: Depends on the battery and if it has the protection circuit, not all do and they're not all equal.Some do everything, low voltage cutout, high voltage cutout and over-current protection.Others just do some protection but not others.And some batteries have no protection at all.

author: peter.mitchell
author_rank: Super Contributor
timestamp: November 12, 2012, 07:11:14 am
content: Generally, the LVCO on the circuits provided with the battery are "emergency" cut-offs, and they cut the power when the voltage is far lower than a recommended level, if you use these as your primary LVCO you will significantly lower the batteries lifespan.

author: MikeK
author_rank: Super Contributor
timestamp: November 12, 2012, 08:31:40 pm
content: I think any solution might end up consuming more current than I'd like. It's a wireless device, so I suppose I could just send the voltage along with the other data and keep an eye on it.
Not expected rising current in Sleep mode - Page 1
Forum section: electronics / beginners

author: adhoc_user
author_rank: Contributor
timestamp: October 10, 2019, 08:37:20 am
content: Hi folks,we are testing our stm32L4 with a LoRaModule (SX1278 named as RA-02).We always (tested with 2 boards) have a unexpected rising curve of the current after a TX-transmission or touch event.If we push the RA-02 module to a side with little force or touches some pads of the module the current is falling to the real sleeping current(µC is sleeping).But a few seconds later the current is rising again. And the module is well soldered, we have checked every solder joint.If we disconnect the vdd jumper brigde (only for this module) the current has a permanent low value. So the circuit after this vdd bridge to lora should be the problem.What caused the rising current? Bad PCB? Bad Connections?Thanks in advance for hints!

author: adhoc_user
author_rank: Contributor
timestamp: October 10, 2019, 10:12:29 am
content: OK, solved by myself.The lora-module has in sleep mode an active SPI_CS pin, you can wake up the module with spi.By default our µC-pins are in analog mode with high impedance in sleep mode.This pin on sx1278 needs a permanent pull-up in sleeping time. Otherwise its floating and does "something" which cause the extra current.Now we have ~60µA
NOT Gate Ramp Oscillator Equivalent Issue - Page 1
Forum section: electronics / beginners

author: willbanks
author_rank: Contributor
timestamp: March 23, 2023, 05:09:53 pm
content: The images are not uploading properly so I attached imgur links.Hi guys. For a personal project, I have designed a sawtooth oscillator using a NOT gate, capacitor, resistor, and diode shown in the pictures below. For this circuit:R1=1k, C1=1uFD1: General purpose diode with a saturation current of 1e-14, ideal breakdown voltage (infinite).NOT gate:-Ideal Rise/Fall-rise/fall delay of 1e-19-output low = 0V-input threshold = 0.8V-input high threshold = 5VSawtooth:Vpp = 3.312frequency = ~611.6HzThese next pictures is what the equivalent circuit is. I first built this circuit as a typical NOT gate would do. However, it does not function._s=1e-16, beta=100, V_A=inftinityhttps://imgur.com/a/g2HxEkhLet me know if more info is needed, I'd love to understand what is happening. Thank you. I may take some time to respond as I am studying for an exam.
Not reading Current - Instek GDM-8251A - Page 1
Forum section: electronics / beginners

author: mikefromsac
author_rank: Contributor
timestamp: January 21, 2017, 05:45:18 pm
content: I just received a used Instek GDM-8251A from Ebay. I believe it was part of a liquidation sale. It seems to work perfectly except I can't test current. Neither AC or DC reads anything in the meter, yet I can read the current perfectly on my Fluke 87V hooked up the same way. I'm a bit of a noob but I checked the front fuse and it was fine. Are there internal fuses I need to check or another fix? I'd hate to have to box and ship back as I really like it.

author: jeroen79
author_rank: Frequent Contributor
timestamp: January 21, 2017, 06:01:56 pm
content: Does the current not flow through the meter at all or does the meter just not give a reading?Does it indicate 0 current or something weird?Is it the same for the 2A and the 10A inputs?Are the other functions good?

author: flash2b
author_rank: Regular Contributor
timestamp: January 21, 2017, 06:28:50 pm
content: Put it in current mode and continuity test it with your Fluke.It should be low ohm otherwise it is likely a blown fuse inside the meter.

author: mikefromsac
author_rank: Contributor
timestamp: January 21, 2017, 07:51:44 pm
content: Current does not flow through the meter. I'll open her up and look for more fuses.

author: mikefromsac
author_rank: Contributor
timestamp: January 21, 2017, 10:00:47 pm
content: Hi Guys, thanks for the info. I found a blown KTK-12 Fast-Acting fuse in the 10A area of the board, so I ordered a couple to arrive late next week. I’m guessing this will fix it unless there’s a reason it blew, other than a one-time occurrence.

author: mikefromsac
author_rank: Contributor
timestamp: January 29, 2017, 04:12:15 am
content: The fuse was the problem and she works perfectly now, thanks for the help!

author: flash2b
author_rank: Regular Contributor
timestamp: January 29, 2017, 06:55:15 pm
content: Good to hear that! Enjoy your nice meter!
Not sure about purpose of DSO accessories - Page 1
Forum section: electronics / beginners

author: luxfx
author_rank: Contributor
timestamp: June 14, 2016, 03:26:53 pm
content: Long story short, I'm in a financial position to realize my long term electronics interest, and have a breadboarded circuit in mind I'd like to pinnochio into a Real Product. I'm adding some Real Tools to my workspace now.I'm looking at theRigol DS1054Z Kit1on TEquipment. It's been a decade+ since I've used an oscilloscope and I'm not too sure about a couple of the accessories.50 ohm feed through-- what's the purpose of this? I've seen online that 50 ohms is some sort of standard for this but I'm not sure why or what purpose it serves.T adapter-- when/how do you use a T adapter? Maybe triggering from either of two inputs? Can signals be combined, like an AC+DC offset waveform?Thanks!

author: rstofer
author_rank: Super Contributor
timestamp: June 14, 2016, 03:36:39 pm
content: When you feed a signal from a generator with 50 Ohm output impedance, you might want to terminate the coax with 50 Ohms right near the load. I thought the 1054Z had a 50 Ohm selection for the input impedance but I can't find it. So, I would use the terminator to match the impedance right at the scope BNC.

author: Unknown
author_rank: Unknown
timestamp: June 14, 2016, 03:56:10 pm
content: Hi, both of those accessories are for use with 50 ohm coax cables not the standard probes that come with the scope. The feedthrough terminator is used if you want to measure in a 50 ohm environment (common in RF circuits) as the scope doesn't have an internal termination. The tee adapter just lets you connect 2 cables to a single channel input. This can be used to 'tap' off a signal in a coax setup eg: Sig gen > scope > circuit, preserving the coax characteristics.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: June 15, 2016, 12:31:55 pm
content: The DS1054z does _not_ have selectable 50 ohm input impedance, all channel inputs are fixed at 1 Megohm.It looks like that kit1 includes 2 50-ohm feedthrus, one the Rigol part and one the CT brand part.Some of the cables/adapters will be more useful with your FG and DMM than with the scope, but yes, all those items are good to have on hand.

author: luxfx
author_rank: Contributor
timestamp: June 15, 2016, 03:59:38 pm
content: Thanks! I'm shopping for a FG this week, and my BM869s should arrive any day now.... Quite a step up from the $18 and free-with-purchase meters I've been using!
Not sure about testing diode in circuit - Page 1
Forum section: electronics / beginners

author: taste_tester
author_rank: Regular Contributor
timestamp: May 06, 2022, 07:04:02 am
content: I was trying to find a fault in this schematic to find my faulty component.I tested all the values shown and everything was correct and in specI did diode test on CR13, CR14.Vdrop with the leads facing the normal direction, 0.64v.Vdrop with the leads facing the wrong direction, 1.715v.I thought there should be nothing in the wrong direction, but i'm not sure because I'm testing in circuit.Both diodes show the same measurement, within 0.02v +/-.Should I replace the diodes? Or are they not the problem?

author: wn1fju
author_rank: Frequent Contributor
timestamp: May 06, 2022, 11:26:51 am
content: Those diodes are use to clamp the voltage. They are most likely OK and the reverse reading you are getting is the result of looking back through the power supply and other circuitry. If you want a definitive test, simply de-solder one of the leads of each diode and test them that way.I would also suggest you look at the op-amp. A very simple check is to measure the voltages at the inputs - they should be the same when the unit is operating. Pins 5 and 6, and pins 9 and 10 should all be at zero volts.
Not sure how to read datasheet SN74HC595 - Page 1
Forum section: electronics / beginners

author: dsharp02
author_rank: Contributor
timestamp: April 23, 2016, 02:01:05 am
content: http://www.ti.com/lit/ds/symlink/sn74hc595.pdfI'm trying to understand how to use the 74HC595 and I think I understand what I need to do. Here is my understanding, please correct me if I'm wrong...To shift a bit into the shift register:1. Pull OE low.2. Wait for a falling edge on SRCLK.3. Set SER to the desired bit value.4. Wait for the next falling edge on SRCLK.5. Set RCLK high, and hold until a rising edge on SRCLK.Does SRCLK have to run continuously if I'm not using the chip? Or can I start pulsing SRCLK only when I need to use the chip. Will stopping SRCLK clear the current output?Also, I'm not sure I understand how to read section 7.6 Timing Requirements.What are do the different parameters represent?tpd - ?tPHL - ?tt - ?Thanks,Dave

author: bson
author_rank: Unknown
timestamp: April 23, 2016, 04:36:30 am
content: tpd= propagation delay time/OE controls the outputs and if pulled high causes them to go into a high-impedance state. Low, the outputs reflect the storage register. If you don't need tri-state functionality just wire it to ground.SRCLK moves the shift register one stopRCLK copies the shift register to the storage register registerThis permits you to clock in say 8 bits of serial data to be output together. If RCLK and SRCLK weren't separate each SER bit clocked into the shift register would cause the outputs to change and you'd have spurious output changes, not all 8 bits changing at once.You only run the clocks when you either want to clock in data (SRCLK) or output what's been shifted in (RCLK).Here's how to use it:1. Output a bit on SER2. Strobe SRCLK L-H-L3. Repeat for all bits4. Strobe RCLK L-H-LThat's it. You can also connect RCLK to a /CS signal for SPI. In that case connect MOSI to SER and SCLK to SRCLK. RCLK will be held low initially (blocking output changes), 8 bits will be clock into the shift register, and RCLK raise back to high outputting the 8 bits.
Not to be a jerk, im going to be trying to fix my Monitor and a tv given to me - Page 1
Forum section: electronics / beginners

author: Astaldoath
author_rank: Contributor
timestamp: June 11, 2018, 06:49:48 pm
content: Both have bad powerboards. I just bought my iron the ts100 with the b2 tip i believe. Can anyone send me like 1/2 oz or 1/4oz of kesser 0.031 solder? I dont have enough to buy the 1 lb for 26-28 bucks atm, i Just need a little to basically, stick on 7 caps if i replace all the ones on the monitor, 1 tiny button on my xbox mini controller for my pc, and most likely 3-8 caps on the television. If anyone is able to do that for free id be eternally greatful. Im pretty sure im not supposed to do this, and feel free to say no or if you have a source i can spend like 5 bucks for some good 60/40 solder with good rosin core in it lemme know. I just dont have enought to fork out almost 30 with shipping atm. If you know somewhere that sells small tubes of the stuff. I got a small tube from walmart, its probably just, i know its too think for my little shoulder button on my gamepad. The caps it may work for. There is just no where in my town I can get anything like this.If this is inappropriate to ask, feel free to delete it guys, im not trying to be a jerk at all. I mean i dont expect anyone to send anything over what would fit in an envelope with a stamp if they feel like it. Otherwise. I will post results and pics after I fix or try to fix these items. Ill get my iron on the 15thWish me luck.

author: Nusa
author_rank: Super Contributor
timestamp: June 11, 2018, 07:08:41 pm
content: https://www.ebay.com/sch/i.html?_nkw=kester+.031+solder&_sacat=0&LH_TitleDe&_udhi=6&_sop=15

author: Astaldoath
author_rank: Contributor
timestamp: June 11, 2018, 07:49:01 pm
content: np, and thank you, people said avoid ebay for kesser because you can get fake solder, ill try one of the links u guys provided me, thanks guys

author: retiredcaps
author_rank: Super Contributor
timestamp: June 12, 2018, 12:30:14 am
content: For monitor and TV repairs, I just use the 60/40, sort by lowest price, solder off ebay. It is usually 99 cents + free shipping.Works well enough for me to repair several monitors and TVs with bad capacitors.Your mileage may vary.
Novel Self-Boosting High-Side Driver Circuit Simulation - Page 1
Forum section: electronics / beginners

author: MajorEE
author_rank: Contributor
timestamp: January 01, 2023, 12:39:49 am
content: Hey Folks,I found this novel circuit for a self-boost charge pump and am unable to duplicate their results in simulation. Would someone mind providing some assistance?In particular I have simulated everything using Altium and get no boost action out of the capacitor circuit with or without a load.Presumably I am doing something wrong because conceptually this circuit should function, however, the paper did note they used piecewise-linear models.Their parameters:- VDC 600V- CL 10uF- VCC 20V- CH 10uF- Rg 2k- f 5kHz- R3 2k- Ro 600Attached is the simulation example and the circuit.Reference paper:A Self-Boost Charge Pump Topology for a Gate Drive High-Side Power Supply- DOI: 10.1109/APEC.2003.1179203-https://ieeexplore.ieee.org/document/1179203

author: jonpaul
author_rank: Super Contributor
timestamp: January 01, 2023, 02:04:59 am
content: Easier to just build it perhaps 10 min if you have the papers and lab power, pulse genJon

author: Terry Bites
author_rank: Super Contributor
timestamp: January 01, 2023, 03:56:28 am
content: Try setting up a charge in one of the caps in the initial conditions.Make sure steady state or operating point is set to off.
Noyafa NF-8508 - Page 1
Forum section: electronics / beginners

author: numloxx
author_rank: Contributor
timestamp: August 15, 2023, 02:56:53 pm
content: Hi all,Thinking of buying a cable tester and was wondering if anybody had used this before?Noyafa NF-8508I know Dave had a look at the 8601 before.
NPN BJT Power Supply & FuncGen - Page 1
Forum section: electronics / beginners

author: stafil
author_rank: Regular Contributor
timestamp: June 05, 2020, 08:29:18 am
content: Is it safe to have a power supply connected to the Collector of an NPN BJT and use a funcgen to drive the the base and have a common ground?

author: exe
author_rank: Unknown
timestamp: June 05, 2020, 10:49:22 am
content: Schematic would help...Anyway, I'd use a current-limiting power supply with floating output, and used a base resistor to drive the bjt.What's your intention?

author: stafil
author_rank: Regular Contributor
timestamp: June 05, 2020, 06:13:28 pm
content: Quote from: exe on June 05, 2020, 10:49:22 amSorry, I wrote this before going to bed. Attached is the schematic and what I see on the scope.V1 is the power supply, V2 is the func gen. Func Gen config is 1kHz Frequence, 1V Amplitute, 2V Offset. The BJT is a 2N3904.Pink is a probe at base, Yellow at emitter.My intention: I was having trouble with a collpitts oscillator output, it was distorted, so wanted to check if I am indeed in the linear region of the transistor

author: David Hess
author_rank: Super Contributor
timestamp: June 05, 2020, 11:15:45 pm
content: Yes, it will work fine as long as the output from the function generator does not go negative enough to cause reverse breakdown of the base-emitter junction, which will occur below about -5 volts in this case.

author: exe
author_rank: Unknown
timestamp: June 06, 2020, 12:19:51 pm
content: I see you are using a generic model for npn transistor. My advice is always specify transistor type (such as 2n2222). Ideally it should match your actual transistor. In my experience generic models are often way too far from real parts.Or, put in a different way, the simulation is as accurate as models are. Generic models for transistors are way to generic to be useful.
NPN offset AC - Page 1
Forum section: electronics / beginners

author: electrolust
author_rank: Unknown
timestamp: November 07, 2015, 12:00:32 am
content: I understand that a BJT NPN can transmit AC from base to emitter if the signal is biased. Seems easy enough.A 2-wire electret mic input will put bias voltage out on the mic-in jack. Then the mic is powered from the bias voltage and sends the signal "backwards".Given that this signal has bias and does not cross below ground, I figure it can pass across emitter to base. My simulation at circuitlab doesn't quite agree. There is a signal but it is orders of magnitude too low, and it isn't offset.Something wrong with my circuit, or something wrong with circuitlab? I suspect the former ...The AC signal source is 100mV p-p at 1k. I'm only getting a 1uV RMS signal back.

author: Andy Watson
author_rank: Super Contributor
timestamp: November 07, 2015, 12:13:18 am
content: You need a load on the emitter to cause the transistor to function. Without the load the transistor is not turning-on. The signal that you are seeing at the output is probably due to (very small) capacitance between the base and emitter.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 07, 2015, 12:16:42 am
content: Welcome to shitty simulators...A true voltage source (as apparently used, as shown) carries DC no problem, so it should be biased (albeit suicide biased). Methinks the 10V source isn't actually working at all, or the BJT model used is utterly pitiful.Tim

author: Andy Watson
author_rank: Super Contributor
timestamp: November 07, 2015, 12:27:43 am
content: Quote from: T3sl4co1l on November 07, 2015, 12:16:42 amYou think that "V2" is actually signal source? In that case I've made a wrong assumption - so where are we looking for the output?Edit: I think I have totally mis-understood what is being asked here

author: Marco
author_rank: Super Contributor
timestamp: November 07, 2015, 02:36:29 am
content: You're pulling nearly 9 mA of base current through that poor transistor.Even if you connected V2 to the emitter with a capacitor and put a resistor to ground and made the whole circuit a little more realistic it simply doesn't make much sense to read voltage back from the base, you're amplifying the transistor noise. You could turn it into a common base amplifier with a collector resistor, but common base amplifiers also don't really make sense here.If you want to bias the electret simply connect it through a resistor (divider) to the bias voltage and AC couple it to an amplifier.
NPN & PNP LTspice - Page 1
Forum section: electronics / beginners

author: Spitfire1.2
author_rank: Newbie
timestamp: February 04, 2020, 02:00:44 pm
content: Hello!I a bit confused with a circuit on LTspice and I need your help if possible.I tried simulating the following circuit, from my calculation the power on the Led should be around 20mA, but the simulated circuit shows 1.07mA. I tried the same circuit on other simple online simulators like part-sim and falstad and I got the 20mA. Is there something critical that I am missing? Or is it a design error in LTspice?Thanks for your time!

author: EEEnthusiast
author_rank: Frequent Contributor
timestamp: February 04, 2020, 02:06:30 pm
content: Can you reverse the C & E of Q2 and try again?

author: rstofer
author_rank: Super Contributor
timestamp: February 04, 2020, 03:09:17 pm
content: What's R5 suppose to represent?

author: StillTrying
author_rank: Super Contributor
timestamp: February 04, 2020, 03:34:14 pm
content: And what does R3 do, it just looks like a jumble of components to me.

author: Spitfire1.2
author_rank: Newbie
timestamp: February 04, 2020, 05:12:31 pm
content: R5 is the Led resistor, sorry but I accidentaly moved it. R3 is simulating a load on the NPN. The PNP was reversed, i took it for granted that the collector was on the botton. Thanks for the help!

author: Zero999
author_rank: Super Contributor
timestamp: February 05, 2020, 12:24:58 pm
content: What is the circuit supposed to do?Try varying the supply voltage and see what happens to the LED current.
NPN SMPS transistor substitute - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: August 06, 2021, 01:01:01 pm
content: Cheap Chinese, Ebay sourced 28V at 17 Amps (yeah, right...) SMPS has blown an output transistor and cap. Can I substitute these D13009K originals with these MJW18920 devices, pdf's linked below. Thanks.

author: wraper
author_rank: Unknown
timestamp: August 06, 2021, 01:11:41 pm
content: D13009K is a clone of MJE13009
NPN transistor as video amplifier : how to adjust brightness? - Page 1
Forum section: electronics / beginners

author: caius
author_rank: Regular Contributor
timestamp: July 08, 2020, 02:29:47 pm
content: Hi all,I'm designing a a video amplfier (one for each RGB color) using a simple NPN transistor.The circuit works pretty well but the image is a little darker to what I really want.Specifically the signal coming to the base of transistor is the result of a R/2R resistor adder that converts the digital bits from a CPLD to analogHow can adujst brightness?I changed the value of the two resistors 'R9' and 'R2' which forms the voltage divider for the transistor biasing but this only led to little improvement.Thanks in advance for any help/suggestionP.S.Also replacing the 10 ohm resistor with 75 Ohm for proper impedance as well as using different transistors with more gain did not have effect.

author: magic
author_rank: Super Contributor
timestamp: July 08, 2020, 03:43:20 pm
content: That's not an amplifier, it's an emitter follower. Its gain is unity, emitter voltage is base voltage shifted down by 0.7V or so.I know nothing about video signaling so can't offer much help.Beware that you have DC on the output and this may blow up termination resistors in whatever display you are driving unless it has internal AC coupling (?).Output impedance of emitter followers is not exactly zero, more like 25~30mV divided by collector current. 75Ω of additional termination resistance is certainly too much. It still makes little difference for signal amplitude, though, as you observed.

author: Benta
author_rank: Super Contributor
timestamp: July 08, 2020, 07:59:13 pm
content: The correct way of doing video buffering is using an NPN emitter follower followed by a PNP emitter follower. This ensures that the video DC level stays intact. Download any old VCR service manual, you'll see this type of buffer all over the place in the schematics.
NPN transistor base resistor voltage spikes? - Page 1
Forum section: electronics / beginners

author: Agony
author_rank: Contributor
timestamp: April 25, 2013, 12:44:49 am
content: Run the simulation and noticedthe unusual voltage spike inbetween theresistor and base.Would it be a bleedthrough from the 12V on collector?

author: MikeK
author_rank: Super Contributor
timestamp: April 25, 2013, 02:52:21 am
content: Your third attachment is empty.

author: Agony
author_rank: Contributor
timestamp: April 25, 2013, 01:36:00 pm
content: weird... this should do then:

author: Agony
author_rank: Contributor
timestamp: April 26, 2013, 12:45:14 am
content: Could it be a simulation error or a kind of inductive voltage spike?Alltho its within limits and wouldnt damage the transistor, and the extra current it would let through wouldnt be a problem in current case - its still unwanted.How would you go about smoothing it out?Was thinking of a zener with a low breakdown voltage (in that case 0.9V) right inbetween the resistor and base with one end grounded.So it would ground any spikes.https://www.circuitlab.com/circuit/p3uvb3/npn-transistor-switch/Tho that resulted in a waveform that has slightly less voltage at the beginning of each cycle and a spike in current at the end.

author: croberts
author_rank: Regular Contributor
timestamp: April 26, 2013, 01:14:33 am
content: Hello AgonyI ran the simulation and do not see the spikes. I attached the image.

author: Agony
author_rank: Contributor
timestamp: April 26, 2013, 02:27:29 pm
content: yes, i currently added the D2 zener wit h around 0,9V of breakdown voltage so it grounds the spikes, if you remove/disconnect it, the spikes show up.

author: w2aew
author_rank: Super Contributor
timestamp: April 26, 2013, 02:51:44 pm
content: This is most likely a defect in the model for the 2N2222 in the simulator. Models aren't perfect, and some are less perfect than others, especially for modeling non-linear, large-signal behavior.
NPN transistor numerical  - Page 1
Forum section: electronics / beginners

author: khatus
author_rank: Regular Contributor
timestamp: November 08, 2018, 03:57:36 am
content: Can anybody solve the following problem?? and posts each steps of solution if possible

author: khatus
author_rank: Regular Contributor
timestamp: November 08, 2018, 04:42:10 am
content: STEP-1: At first i apply KCL at node x. which give meThen how i can proceed further??

author: IconicPCB
author_rank: Super Contributor
timestamp: November 08, 2018, 04:49:08 am
content: Vc = 9- Rc*IcIC = 45 * IbIb = Ira - IrbIra= (Vin-0.7)/RaIrb = 0.7/Rb

author: khatus
author_rank: Regular Contributor
timestamp: November 08, 2018, 05:02:29 am
content: So the node voltageVx = VBE (base emitter voltage) ??

author: bson
author_rank: Unknown
timestamp: November 08, 2018, 07:31:39 am
content: Quote from: khatus on November 08, 2018, 05:02:29 amWell, yeah. The only thing between it and ground is B-E, which is 0.7V.

author: khatus
author_rank: Regular Contributor
timestamp: November 08, 2018, 12:37:38 pm
content: Same problem with an additional base resistorI think the steps will beSTEP-1:Vx- VBE= IB×RESTEP-2:IB = Ira - IrbSTEP-3:Vx= VIn×(RB/RB+RA)Please tell me i am correct or not??

author: LvW
author_rank: Frequent Contributor
timestamp: November 08, 2018, 03:45:59 pm
content: No step 3 is not correct.For the voltage Vx ALL THREE resistors and both voltages Vin and VB are to be considered.And you are allowed to treat VB as a voltage source with VB=0.7V.
npn/shcmit trigger ic - Page 1
Forum section: electronics / beginners

author: peterthenovice
author_rank: Regular Contributor
timestamp: March 23, 2013, 07:31:37 pm
content: hi i am looking for a npn transistor/schmit trigger ic. iam trying to build this generator

author: Thor-Arne
author_rank: Unknown
timestamp: March 23, 2013, 08:27:45 pm
content: Any inverter schmitt trigger inverter should be fine, like 74HC14.Note that this one can operate from 2V to 6V.

author: peterthenovice
author_rank: Regular Contributor
timestamp: March 23, 2013, 08:29:08 pm
content: I am looking for a chip that hasboth a shcmit trigger and transistor.

author: w2aew
author_rank: Super Contributor
timestamp: March 23, 2013, 09:28:22 pm
content: Quote from: peterthenovice on March 23, 2013, 08:29:08 pmYou won't find one.
NRF24L01 with UNO - Page 1
Forum section: electronics / beginners

author: jenniferkim
author_rank: Contributor
timestamp: July 18, 2021, 02:01:49 am
content: Hi,I am working onNRF24L01module and it's giving me the error "Response Timed Out". I am unable to resolve it.One more thing, what's the difference between NRF24L01 and NRF24L01+ ? Can I communicate between them as well ?Thanks.
nRF24L01 - Page 1
Forum section: electronics / beginners

author: plee
author_rank: Newbie
timestamp: July 23, 2016, 08:00:37 pm
content: Hi all,I have a nRF24L01 and was wondering if there are any software libraries that can allow it to connect to my internet?

author: ataradov
author_rank: Super Contributor
timestamp: July 23, 2016, 08:29:35 pm
content: Quote from: plee on July 23, 2016, 08:00:37 pmAssuming that by "internet" you mean Wi-Fi, then no, not even close.You need ESP8266 or similar Wi-Fi IC/module.

author: rudika79
author_rank: Regular Contributor
timestamp: July 23, 2016, 08:39:39 pm
content: Hi,You can not connect directly to your wireless internet. nRF24L01 IC is not WIFI module. nRF24L01 IC (module) is 2.4GHz RF module with own communication protocol. You can read the datasheet for more details. You can use arduino with ethernet or wifi shield to make internet gateway to nRF24L01 radio network. You can check outhttps://github.com/maniacbug/RF24library. They have Arduino and Raspberry Pi library.
NS resistor  - do not stuff ?!?! - Page 1
Forum section: electronics / beginners

author: SnakeBite
author_rank: Regular Contributor
timestamp: May 16, 2014, 11:12:55 am
content: Hi,i saw in some datasheet a resistor that the value is "NS" and the description says "do no stuff" .WHAT IT MEANS?thanksIdo

author: sleemanj
author_rank: Super Contributor
timestamp: May 16, 2014, 11:27:30 am
content: Quote from: SnakeBite on May 16, 2014, 11:12:55 amIt means that part should not be installed on the PCB (by default, it may be required for testing, or some other option).

author: SnakeBite
author_rank: Regular Contributor
timestamp: May 16, 2014, 11:49:41 am
content: thanks

author: amyk
author_rank: Super Contributor
timestamp: May 16, 2014, 11:59:54 am
content: I've also seen "DY" used as an abbreviation for "part not installed" --- would be nice to know where that convention came from.

author: richard.cs
author_rank: Super Contributor
timestamp: May 16, 2014, 01:53:38 pm
content: I usually see them marked as "DNI" for do not install or "No fit". There are a lot of reasons you might do that, generally when designing a PCB it's good to give yourself the option to make changes to the design in the future without changing the PCB.You might also see "SOT" for select on test. That's normally a sign that it's either a prototype or a seriously marginal design that needs hand tweaking.

author: krivx
author_rank: Frequent Contributor
timestamp: May 16, 2014, 02:09:13 pm
content: I'm used to DNP for "Do Not Populate". Quite common when you think an amplifier might need a compensation capacitor in the feedback loop but can't be sure until you get the boards and build it, you put in a footprint for safety.

author: theatrus
author_rank: Frequent Contributor
timestamp: May 16, 2014, 09:01:56 pm
content: I've also use POP: Populate OPtion. Usually for multiple designs with the same basic board, or a designed-in-cost-reduction

author: Lizerd
author_rank: Contributor
timestamp: May 16, 2014, 09:05:59 pm
content: Another standard is that the component value is "xx"

author: David_AVD
author_rank: Super Contributor
timestamp: May 16, 2014, 09:08:15 pm
content: I've seen DNF (Do Not Fit) and DNP (Do Not Populate) on a number of schematics.

author: LukeW
author_rank: Frequent Contributor
timestamp: May 17, 2014, 04:46:10 am
content: DNI, NP, DNP, DNF, POP, SOT, DY, NS...It would be good if we could all come to one single standard for this which is understood worldwide.

author: uoficowboy
author_rank: Regular Contributor
timestamp: May 17, 2014, 03:45:53 pm
content: Quote from: LukeW on May 17, 2014, 04:46:10 amYou left out DNS! (do not stuff)I agree that it'd be nice to have a standard. It seems like each company that I work for has their own standard for this.