hybridfree/eevblog-posts huggingface dataset:
High voltage measurement of quasi isolated power supply - Page 1
Forum section: electronics / beginners

author: Momchilo
author_rank: Regular Contributor
timestamp: July 25, 2019, 07:17:08 pm
content: Hi,I have to measure voltages of an galvanic isolated system with ADCs. The V_IN voltage is around 70V DC or 50V AC.The idea is a difference measurement. It's not galvanic isolated anymore, but isolated through the high input impedance. So it's quasi isolated like differential probes for scopes. In Spice simulations it works very well.Do you think this will work with an isolated V_IN without destroying anything even at higher voltages (<200V) or make it dangerous for a person?Because the other grounds in the schematic are the analog grounds for the amplifiers and the ADCs. It's connected to the digital ground in one point. If you think, this will work, I'm unsure where to connect pin 1 of the AD629. Should it be connected to the analog ground or the isolated ground? I guess to the isolated one.Thanks for your advice.Best regardsMomchilo

author: David Hess
author_rank: Super Contributor
timestamp: July 25, 2019, 10:43:03 pm
content: Yes, it should work but where did you find that circuit?The OP177 integrator is there to remove the DC component from the AD629's output without using input AC coupling capacitors which are problematic. The result is that the AD629's output has a high pass characteristic and the OP177's output has a low pass characteristic. Is that what you wanted?In normal applications, both pin 1 and pin 5 of the AD629 goes to the same output ground. In this case, I think pin 1 should go the same ground as pin 3 of the OP177. There is no direction connection to the isolated ground except through the device.

author: Momchilo
author_rank: Regular Contributor
timestamp: July 26, 2019, 04:58:28 am
content: Thanks for the answer, you helped me a lotI found this in "A Designer's Guide to Instrumentation Amplifiers" released by Analog Devices. You can download the whole PDFhere. The used circuit with a short description is on page 92.How would you change the circuit?At least in the PSpice simulation it works really well up to 100kHz. There is only 1dB attenuation in the output signal at 100kHz. That is more than enough for the measurements.Then I will connect all grounds (except the isolated one) to analog ground.

author: David Hess
author_rank: Super Contributor
timestamp: July 26, 2019, 02:20:55 pm
content: Quote from: Momchilo on July 26, 2019, 04:58:28 amAh, I think I remember an earlier edition of that book. Analog Devices has released some of the best documentation over the years.QuoteI might not change it at all. it is one of the better options for your requirements.QuoteThe value of C1 can be increased to lower the bandwidth which may be important to control noise. Attenuating input instrumentation amplifiers are pretty noisy.
High voltage on a USB-C connector shield, any reason to worry? - Page 1
Forum section: electronics / beginners

author: TheAmmoniacal
author_rank: Unknown
timestamp: April 30, 2025, 11:56:43 am
content: I have a custom built mini-ITX computer, which uses a Corsair SF600 power supply and an MSI MPG B650I EDGE WIFI motherboard. I had a USB-C cable connected to the motherboard (I/O area) dangling while I was fixing some wiring, and could feel a tingling/stinging sensation as it rubbed against my skin. This sensation got stronger if I pushed it against the skin or against sweaty skin... I then measured it with a multimeter (high impedance) and got 114 VAC between the shield of the USB-C connector and protective earth (PE).I then did some testing and found out my PC power cable did not have an earth conductor, I replaced the cable with a good one and now there's no issue anymore.Is this expected "leakage" current? Or is this something I should get fixed? What happened and why does the PE fix it?

author: Zero999
author_rank: Super Contributor
timestamp: April 30, 2025, 12:07:01 pm
content: It was most likely leakage due to the Y suppression capacitors. Connecting the earth fixed the problem, by providing a path to earth, for the leakage current.

author: mtwieg
author_rank: Frequent Contributor
timestamp: April 30, 2025, 01:11:20 pm
content: Yes, what you're describing is a textbook example of leakage current.Normally the protective earth (PE) connection in the power cord acts as the return path for all leakage currents. But when that PE connection isn't present, then that current will find whatever return path to earth it can find, including you.If you were to switch your DMM to measure AC current and measure from the shield to PE, you're basically measuring that leakage current. Safety standards put limits on the leakage current (for example 3.5mA for IEC 60950-1).
High voltage output on same sensor pads as low voltage touch input? - Page 1
Forum section: electronics / beginners

author: trifusion
author_rank: Contributor
timestamp: February 21, 2025, 07:28:56 pm
content: I have a thought on something I would like to build but because I have not seen it built before it makes me think it may not be possible ...Is it possible (in a simple way) to take a cheap prank shock toy like thishttps://www.aliexpress.com/item/1005006528974068.htmland check to see if a finger is touching both sides of the metal plate?I would like to ideally use the touch sensor feature of the ESP32 pins but I'm not sure how to wire it so I can read a touch but also provide a high voltage shock without destroying the ESP32 pins.There is a mechanical switch way of doing it like this example:But I was hoping to use a electronic touch sensor way if possible but I'm not sure if non-mechanical ways would be too susceptible to arcing because of the high voltage.Any thoughts?ThanksGreg

author: benj38
author_rank: Frequent Contributor
timestamp: February 22, 2025, 09:40:11 pm
content: A relay?

author: trifusion
author_rank: Contributor
timestamp: February 24, 2025, 01:57:22 am
content: Seems like from the electronoobs video I posted that the relay will short with the high voltage and not sure even if I used a relay how I could protect the touch sensor pins on the ESP32?

author: benj38
author_rank: Frequent Contributor
timestamp: February 24, 2025, 11:29:29 am
content: The idea is that the relay disconnects the sensitive electronics from the pads and after a short delay you apply the high voltage to the pads.Note that the relay never switches the high voltage, it switches only the sensor voltage. Hence, the important spec you are looking for is not the switching voltage capabilities of the relay, but rather the dielectric strength specifications.Reed relays are usually the champions here. If you plan to have just a couple of kilovolts, the relay may be quite cheep, if you need 10 kilovolts, each relay may set you back around $50, so it may end up to be an expensive toy.
High voltage Plate Transformer - Page 1
Forum section: electronics / beginners

author: Ron Reeland
author_rank: Newbie
timestamp: April 23, 2017, 01:27:56 am
content: Hi:My son is experimenting with vacuum tube operated Tesla Coils. So he has purchased a few very large plate transformers with 2950 AC output volts and higher. One in particular is a Stancor P-8035( weighs 80 lbs). A listing of it in an old Stancor catalog says it "May be used with secondary C.T. ungrounded."However, a transformer just above, P-2126 ( weighs 95lbs), says "Secondary center tap must be grounded." This transformer rated at 2900 AC ouput volts.These transformers likely were to be used in full wave center-tap rectifier circuits.Why does one require center tap be grounded while the other does not? We are concerned thatothertransformers without reference data available could be damaged if not properly grounded. That would negate the use of transformers with a full-wave bridge rectifier circuit.Thanks,Ron reeland

author: tautech
author_rank: Super Contributor
timestamp: April 23, 2017, 02:59:57 am
content: Grounding the CT supplies 2 windings that are likely to be 1800out of phase whereas without the CT grounded it'll be effectively 1 winding @ twice the voltage and that's where the limitation most likely is: isolation/insulation. 6KV is not a trivial voltage to insulate, transformers of this caliber are normally dipped and/or potted to prevent breakdown.Be bloody careful with it as it's weight (lots of copper) would suggest it's capable of more than just a few mA's at the secondary.

author: David Hess
author_rank: Super Contributor
timestamp: April 23, 2017, 08:25:29 pm
content: Many of these plate transformers had two versions with one requiring the center tap to be grounded and the other allowing either end to be grounded. If the center tap is grounded, then the voltage on either leg to ground is half the voltage compared to if a full wave bridge rectifier is used with one leg of the rectifier grounded. The difference in transformer construction is the insulation.
High Voltage power supply - does this sound bad? - Page 1
Forum section: electronics / beginners

author: axawire
author_rank: Contributor
timestamp: June 08, 2021, 02:13:33 am
content: I have a 3kV 30mA neon sign power supply powering a bipolar cockcroft-walton voltage multiplier to get to approximately 30kV, cause I'm poor.however the cockcroft-walton voltage multiplier "hums" when its powered on but not being used, does it sound like electron leakage through the paraffin wax maybe? or is this pretty normal sound with this setup? link to video for reference to sound.https://drive.google.com/file/d/1-kM3NU0T6kx0G-dKixE_F5J8MS1vj_tS/viewIt does however seem to workhttps://drive.google.com/file/d/1KvffFG7MWB534rKdmf40P563k1AHxvns/view

author: PartialDischarge
author_rank: Super Contributor
timestamp: June 08, 2021, 04:23:07 am
content: That seems normal, it’s probably corona from the hv not going anywhere. Also the jumping arc acts as a voltage limiter, which is not present in this case

author: mikerj
author_rank: Super Contributor
timestamp: June 08, 2021, 07:37:43 am
content: Quote from: axawire on June 08, 2021, 02:13:33 amI don't have a neon transformer connected to a multiplier, does that mean I'm wealthy?
High voltage seen when scoping with diff probe - Page 1
Forum section: electronics / beginners

author: Faringdon
author_rank: Super Contributor
timestamp: October 24, 2023, 07:18:05 pm
content: Hi,Today i was probing a circuit where all voltages should have been less than 15V. But the diff probe showed up over 100V where the arrow points in this picture...and LTspice sim.It was as if the diff probe's internal 4MEG was connected to mains line, instead of to earth.What else could have caused this high voltage to be seen?I was probing from Collector to emitter of the BJT, and saw the 100V there, which surely couldnt have been there but i saw it.

author: Gyro
author_rank: Super Contributor
timestamp: October 24, 2023, 07:42:10 pm
content: With a 10uF capacitive divider, where is all the current going to cause the rail voltage to be a mere 15V? I could make a guess at shorted 40V transistors, 555, opto LED etc.EDIT: This may be related tohttps://www.eevblog.com/forum/testgear/scope-waveforms-out-of-sync/who knows.
High voltage spike Generator - Page 1
Forum section: electronics / beginners

author: Monostable
author_rank: Contributor
timestamp: April 18, 2016, 10:13:46 am
content: Hello everyone !This weekend I got my hands on a toroidal transformer with unknown characteristic except that it was made to be used with 110v 400Hz.It has a primary and two secondary (as drawn below)Since I don't have an easy access to 110v 400Hz it was a bit useless to me, so I though why not try to generate some voltage spikes.So I connected the primary in series with a mosfet (IRF540) to my DC power supply, set the voltage at 3V and a current limit at around 50mA.I then connected the gate of the mosfet to function generator and made it output a square wave (0-5V@400Hz).And sure enough when I touched the secondary I felt a little tingling.I tried to measure it with a multimeter it just displayed 23V AC, so I tried hooked it to my analog scope with a x10 probe and sure enough It displayed a spike at 200V around the rising edge of the square wave.So I increased a bit the current limit and the spike's voltage increased, I went to 600V and then decided to stop because I felt that I would blow up my scope's input.I have several questions :Is it safe for my DC power supply to that ?How can I safely measure the voltage spike without damaging my oscilloscopeAt which point does the voltage become dangerous for a human ?

author: danadak
author_rank: Super Contributor
timestamp: April 18, 2016, 10:39:34 am
content: Is it safe for my DC power supply to that ?No, unless you install diode or zener clamps on output.How can I safely measure the voltage spike without damaging my oscilloscopeCreate your own 100X probe with a V divider, but of equal concern is survivability of the MOSFET,exceeding its ratings.At which point does the voltage become dangerous for a human ?https://en.wikipedia.org/wiki/Electric_shockRegards, Dana.

author: Monostable
author_rank: Contributor
timestamp: April 18, 2016, 02:00:50 pm
content: But wouldn't putting a free will diode reduce the voltage spike on the secondary that I am trying to create ?But I don't think I'll be playing around with high voltage anymore, it scares me a bit.Although I did some calculation and I am only drawing (3V/0.05A)w or 0.15w.And if I'm outputting from the secondary 600V (peak) the system can only deliver (0.15w/600V) which is 250µA (assuming there are no losses in the conversion).Although the TRMS value on the DMM was 23V so that would be 6mA.Are my calculation correct to estimate the output capability ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 19, 2016, 02:16:53 am
content: Quote from: danadak on April 18, 2016, 10:39:34 amWhy no?What good will a diode do?Exercise: analyze the circuit and demonstrate that these are useless.QuoteThis doesn't say anything about pulses, though.If the pulse is short, you might not feel it, but it can still cause problems. Best not to touch it in the first place...Tim
High voltage transformer question - Page 1
Forum section: electronics / beginners

author: Greg65
author_rank: Contributor
timestamp: August 11, 2017, 01:44:30 pm
content: Dear forum,I have been given a battery powered 6v-12v electric fence machine to repair that keeps cows and sheep from escaping the field. It can output up to about 5 or 6Kv that connects to a long wire that keeps them from escaping or running out on the road.I have done my tests on the circuit board and the output transformer is blown on the primary side winding. The secondary side of the transformer connects directly to the electric fence wire.I have removed the transformer and checked the primary side voltage on the circuit board which reads about about 6 or 7 volts pulsating on and off so that verifies to me that the control circuit and everything else is ok.The problem is I don't know what type of transformer this is, obviously this a step up from about 6 or 7v to about 5 or 6Kv or so, is this a flyback boost type or a custom made one, I'm not sure!Its a small pcb mount one with no markings at all on it, here are a few photos;Can you tell me what type of transformer this is and where would I get one as I have searched with no results? It doesn't need to be the exact dimensions,Any alternatives would be greatly appreciated?

author: Benta
author_rank: Super Contributor
timestamp: August 11, 2017, 02:26:23 pm
content: Electric fences for livestock work like ignition coils, so yes, it's a flyback.Where to get exactly that on is anybody's guess...

author: floobydust
author_rank: Super Contributor
timestamp: August 11, 2017, 07:54:46 pm
content: Those both look like custom transformers, and the usual capacitive-discharge design.The smaller transformer makes several hundred volts charging yellow capacitors and TO-220 SCR dumps this into the larger HV transformer. SCR usually fails short.The transformer going open occurs usually at the wire bobbin attachment points. I'd take a good look there.Pics are a bit blurry. Otherwise you'll have to get the magnetics from the manufacturer.Got no hits for "TCI".

author: Zero999
author_rank: Super Contributor
timestamp: August 11, 2017, 09:36:56 pm
content: As mentioned above, it's most likely a capacitive discharge circuit. It will be very similar to a stun gun circuit.http://danyk.cz/paral_en.htmlIf the break isn't at the start of the primary, you might sill be able to re-wind it. The primary is usually on the top and secondary in the middle, which makes things easier.
high voltage transistors  - Page 1
Forum section: electronics / beginners

author: malch
author_rank: Regular Contributor
timestamp: June 18, 2014, 02:53:16 pm
content: I thought transistors were only good for may 100 volts, but look at this listing.A thousand volts with no relays!http://www.ebay.ca/itm/FUJI-ELECTRIC-1000V-150A-TRANSISTOR-MODULE-2DI-150Z-100-/271097966519?pt=LH_DefaultDomain_0&hash=item3f1eb2afb7And 150 amps is no slouch either!How do they do it?

author: theatrus
author_rank: Frequent Contributor
timestamp: June 18, 2014, 03:10:20 pm
content: Devices like IGBTs have quite high voltage capability:http://www.digikey.com/product-search/en?pv814=17&pv814=28&pv814=152&pv814=15&pv814=156&pv814=132&pv814=153&pv814=38&pv814=41&pv814=36&pv814=18&pv814=20&pv814=135&pv814=37&FV=fff40015%2Cfff8007e&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25Some classic bi-polar devices can go to 1kV, but they are rarer. Devices like SCRs are 'readily' available in transmission line voltage capabilities.In this case, there are likely a set of parallel IGBT dies bonded into that brick for the current handing capability.

author: malch
author_rank: Regular Contributor
timestamp: June 18, 2014, 03:29:29 pm
content: Hmm I think of "transistors" as analog amplifiers, and thyristors for SCRs or switches.Learn something new every day.

author: iRad
author_rank: Regular Contributor
timestamp: June 18, 2014, 03:40:49 pm
content: Quote from: malch on June 18, 2014, 02:53:16 pmThis is how...

author: jlmoon
author_rank: Unknown
timestamp: June 18, 2014, 04:34:30 pm
content: Grins.. IGBT's are the meat & potatoes of a modern day Tesla Coil.. wooo-hahhahah

author: Shredhead
author_rank: Regular Contributor
timestamp: June 18, 2014, 05:33:44 pm
content: What are you supposed to heat sink it to your car or something?

author: SeanB
author_rank: Super Contributor
timestamp: June 18, 2014, 06:29:37 pm
content: Those high power bipolar devices were very common in ferroresonant UPS devices, as they only needed a simple heatsink about the size of a shoebox to handle 1kVA of power, fed from a 48V battery bank. You also had on there the 2 smaller Semikron SCR half bridges used to charge the battery and provide float voltage control. The only problem was the bipolar blocks were obscenely expensive, and any fault on the driver board meant a blown 400A Dc bus fuse, and one dead transistor block. I took a few apart, the bipolar active device inside is a pair of 1cm diameter disc of silicon, mounted on a aluminia insulator and then bonded to a massive Kovar heat spreader. Leads are thick ribbons for C and E with a thinner set of leads for the base and the emitter sense connections. Later on you had a half meter long heatsink with a lot of parallel 2N3773 transistors on it, using a thin 1mm wire from each emitter as balancing resistors to prevent hotspotting. Fixing was a matter of repairing the driver board, then test it with some 12V lamps in series then getting a box of 100 power devices and a tub of heatsink compound out. One mistake and you have a lot of smoked silicon.
High Voltage/Component Footprint Question - Page 1
Forum section: electronics / beginners

author: insania784
author_rank: Newbie
timestamp: November 12, 2016, 09:58:32 pm
content: I know that for high voltage application a certain clearance has to be maintained to prevent arcs. Knowing this why do some component footprint violate this rule? For example, this diode:http://www.st.com/content/ccc/resource/technical/document/datasheet/34/db/51/35/8d/0b/48/54/CD00003260.pdf/files/CD00003260.pdf/jcr:content/translations/en.CD00003260.pdf.The clearance requirement for 1200V is 6.6mm yet the distance between the pads is 2.63mm. I got my clearance requirement from,http://www.smps.us/pcbtracespacing.html.Thanks

author: Kleinstein
author_rank: Super Contributor
timestamp: November 12, 2016, 10:06:53 pm
content: Some parts may need potting to prevent arcing or excessive surface creep.

author: Zero999
author_rank: Super Contributor
timestamp: November 12, 2016, 10:36:22 pm
content: Quote from: insania784 on November 12, 2016, 09:58:32 pmYou're confusing operational requirements with safety. The diode isn't going to be used for protection against electric shock, therefore the requirements are less stringent.QuoteThe distance of 2.63mm between the pads is much greater than that required for functional insulation at 1.2kV.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 13, 2016, 01:44:19 am
content: You can also route out under the component, so the minimum creepage path is over the component body, and that dimension remains the minimum clearance, which through air will be fine.As Hero999 said, different standards require different levels. One of the most common is harmonized IEC/UL 60950-1. See:http://www.creepage.com/The left frame gives direction for different types of insulation requirements. For example, grounded circuits don't need reinforced isolation to them (a single failure of the insulation results in ground fault current, clearing the fuse or breaker).The right frame calculates the insulation required, which comes from tables in the standard (interpolated as needed and when allowed).This still shows insufficient spacing though. FYI, SMA/SMB/SMC (DO-214AA/B/C, not respectively) packages are quite old and have rather poor tolerances. Manufacturers regularly recommend footprints which do not fit* their own package drawings -- probably because they know their packages are better than the standard (JEDEC DO-xx or whatever it happens to be), but probably also because they don't care much about them either.*Fit, based on IPC recommendations for the type of solder joints used on the package. I mean, they usually at least give a footprint that matches typical dimensions, but rarely do they give a footprint that meets or exceeds the packageworst casedimensions, plus soldering fillet and tolerances.Tim
Highpass - Page 1
Forum section: electronics / beginners

author: Mepakos
author_rank: Contributor
timestamp: September 20, 2019, 08:05:38 am
content: Hi all. If the resistance increases, what changes in the picture on the output signal?

author: hamster_nz
author_rank: Super Contributor
timestamp: September 20, 2019, 08:08:35 am
content: As a thought experiment, increase the resistance to infinity. What do you expect to see?Or what would you expect to see if you decreased it to zero?(No direct answers are ever given to homework!)

author: Mepakos
author_rank: Contributor
timestamp: September 20, 2019, 08:56:51 am
content: Same result i think. Electricity would flow because the resistance doesnt matter?

author: radiolistener
author_rank: Super Contributor
timestamp: September 20, 2019, 10:23:40 am
content: Here is Ohm's law:U = I * RYour circuit is a passive high pass filter. RC cut-off frequency is:f = 1 / (2 * pi * R * C)This is pretty easy to understand what happens if you change R.

author: Zero999
author_rank: Super Contributor
timestamp: September 20, 2019, 03:50:07 pm
content: Quote from: Mepakos on September 20, 2019, 08:56:51 amNope, because the ratio of resistance to capacitance determines the upper cut-off frequency, which affects the step response.How about simulating the circuit?Try simulating it. Start with a 10Hz squarewave, a 100nF capacitor and a 22k resistor.https://www.falstad.com/circuit/
Highside Switching Q? - Page 1
Forum section: electronics / beginners

author: Things
author_rank: Regular Contributor
timestamp: August 01, 2013, 02:34:15 pm
content: Hey all, I'm trying to highside switch 24V from a microcontroller, and I'm spec'ing out some transistors. However I'm having a bit of a mental blank (Why I am designing a PCB at midnight is beyond me), but does the base of the PNP need to be rated for the voltage it's switching? For example I'm looking at the BC817 and BC80 pairs, which have +5 and -5V emitter-base voltages respectively.Dan

author: ignator
author_rank: Regular Contributor
timestamp: August 01, 2013, 04:25:07 pm
content: Do you have a schematic of your circuit?A PNP, I don't see how this works. A NPN (emitter follower), with the collector connected to the +24, the emitter to the load, A resistor from the collector to the base (this turns it on) and the base through a load resistor to an open collector to ground switch.But this configuration is tough if your wanting more then a few milliamps. I've used a self resetting fuse for the collector to base turn on source power (the smallest one Polyswitch had), and a FET from the base to ground, that turns this off. This was intended to act like a normally closed switch. And the FET was used to turn it off.

author: Things
author_rank: Regular Contributor
timestamp: August 02, 2013, 02:01:13 am
content: Like this:

author: Kremmen
author_rank: Super Contributor
timestamp: August 02, 2013, 07:44:12 am
content: This could work. The PNP switch (Q2) base never sees less than V+ - ~0.7 V or so. Q1 and Q2 Vcemax must be rated for the full voltage.
hints and kinks on signal hound analizers - Page 1
Forum section: electronics / beginners

author: ted
author_rank: Newbie
timestamp: October 25, 2012, 12:07:00 am
content: Acquiring a Signal Hound USB-SA44B, specifically to meaure signal levels on inside areas from the Cell Base sites..primarily on 850 and 1900 Bands..Any experiences ,tricks, plotting,vectors etc.. ears and eyes open..on the matter,TksTed
Hipot interference - Page 1
Forum section: electronics / beginners

author: mkwired
author_rank: Newbie
timestamp: August 04, 2012, 05:25:16 pm
content: For most of this week, I spent troubleshooting a torque testing machine that I developed. The system includes a "microcontroller board", a stepper motor controller and motor, a torque meter, and a computer. I quickly fixed all the small problems, but I kept having an intermittent problem where the microcontroller board (Arduino Uno) would stop responding to the computer. The two are connected using a USB serial connection. I found out that the Hipot testing that was happening a few feet from me was causing the problem. Whenever they abruptly shut off the high voltage, the USB connection would stop working.I have attached a picture of the bench with the equipment on it and a screenshot of the electrical impulse that is being created by the Hipot tester. Can someone explain what is going on? The magnitude of the impulse seems only to be affected by how close or far the oscilloscope probe is from the high voltage lead. The scope isn't part of the setup. I'm only using it to see the affect the Hipot machine is having on the local environment.
Hitachi Model VK-C150 Color Video Camera  - Page 1
Forum section: electronics / beginners

author: Johnny10
author_rank: Frequent Contributor
timestamp: May 29, 2017, 03:00:59 am
content: You were all so helpful with the power connector a few weeks ago when I purchased this camera along with a Dynascope Microscope.I purchased the Hirose 10 4 Pin connector and it fits perfectly.Now does anyone know the power connector pinout?I can't seem to find any information on this old camera except that it was used popular as a microscope accessory back in the 90's.Thanks
Hitachi oscilloscope question(power line voltage) - Page 1
Forum section: electronics / beginners

author: reason
author_rank: Newbie
timestamp: August 16, 2012, 11:39:50 am
content: Hello everyone,I recently bought Hitachi V665 oscilloscope from USA but the thing that bothers me is the sign on the back : 120V only.So can i plug it savely to 220V power line?According to service manual the working range is 90-250v AC. It uses STK7308 switching regulator and after it its switching transformer.I dont want to spend additional money for stepdown transformer. What to trust service manual or the sign?Thanks

author: ElektroQuark
author_rank: Unknown
timestamp: August 16, 2012, 01:51:16 pm
content: Quote from: reason on August 16, 2012, 11:39:50 am

author: michaelym
author_rank: Regular Contributor
timestamp: August 16, 2012, 01:57:33 pm
content: I don't know anything about you specific oscilloscope, but the service manual may be for a range of models. And not your specific variation of the oscilloscope.I would trust what it says on the scope.

author: reason
author_rank: Newbie
timestamp: August 16, 2012, 02:15:37 pm
content: Again according to service manual all these models share the same power supply circuit V-1065A-V1060-V665A-V660I dont see any indication that it cannot work with 220V AC line but i'm not 100% sure so that why i'm asking for adviceDatasheet for STK 7308 says 80-280V btw.Further more looking at the schematic there isn't 120V/220V statements . So i'm thinking the whole thing is just different labels for different countries.

author: steve30
author_rank: Frequent Contributor
timestamp: August 16, 2012, 06:53:17 pm
content: I'm not familiar with this particular Hitachi scope, but my lower end one is multi voltage and the voltage is selected by the orientation of the fuse holder, but of course, the correct fuse type must be used. Does yours have this or similar?

author: reason
author_rank: Newbie
timestamp: August 16, 2012, 07:31:31 pm
content: Thanks Steve30, no it doesn't have anything like that, but I took the risk and trusted the service manual despite it says 120V only and powered it up with 220V AC main, guess what it powered up nicely .Mistery solved, I saved up ~20Euro for nothing and the noise that step down transformer will add to this instrument.,(this isn't a hair dryer)I dont blame the japs, more likely the yankees for that label on the back, because their certification system back then, this is old instrument.I will change the fuse for 250V rated one.
Hitachi v152f 15Mhz - Page 1
Forum section: electronics / beginners

author: Skayler
author_rank: Newbie
timestamp: August 28, 2022, 02:28:38 pm
content: Hi guys. My name is Dean.I am new here. I live in Ireland and l am electrician. I have a quastion. I buy oscilloscope Hitachi V152f but l don't have a probes. I search on internet and l didn't find nothing. Can you help me where l can find it. Thank you.

author: Grandchuck
author_rank: Super Contributor
timestamp: August 28, 2022, 04:27:26 pm
content: Hello and welcome Dean. Have you looked at general purpose inexpensive probes as shown at Banggood and Aliexpress?

author: Skayler
author_rank: Newbie
timestamp: August 28, 2022, 04:36:19 pm
content: I didn't becouse l don't know what probes will work and what don't. I don't want buy something and when l connect it doesn't work. I am new in this so l don't know to muck about it. Can you send me a link from amazone or ebay what l can buy.

author: rstofer
author_rank: Super Contributor
timestamp: August 28, 2022, 05:39:07 pm
content: It is likely that there is a label on the panel below the BNC connectors that mentions something like 1Mohm 13 pF (from my Rigol DS1054Z) which is the standard input impedance. Any 1 Mohm X1 probe will work.Like these:https://www.amazon.com/RioRand-PP150-Oscilloscope-Probes-Accessory/dp/B0030KWM30Or you can buy far better probes at ProbeMaster.

author: Skayler
author_rank: Newbie
timestamp: August 28, 2022, 05:46:40 pm
content: Thank you for your help.1

author: rstofer
author_rank: Super Contributor
timestamp: August 28, 2022, 07:03:16 pm
content: FWIW, the probes I linked will have a switch to choose between 1x and 10x. The probe compensation adjustment applies only to the x10 range.Some scopes have a selector to choose between 1X and 10X since 10X clearly affects the display (1/10 as big) and any displayed values will be off by a factor of 10.There is a long scope tutorial linked to the start of this forum. The creator, w2aew, works (worked) for Tektronix and he really knows about scopes. He has a lot of introductory level videos and all are excellent. Google for w2aew, I suppose...I like his op amp and transistor videos. Dave has some good videos in that arena as well.

author: Skayler
author_rank: Newbie
timestamp: August 29, 2022, 01:17:49 pm
content: I will take a look on that videos. I like to learn about this.Thanks.
hitachi v525 help - Page 1
Forum section: electronics / beginners

author: Priestblood
author_rank: Contributor
timestamp: December 12, 2013, 11:53:34 pm
content: Hi allI bought a Hitachi v525 of eBay and I got stung,The problem is running a single channel and the crt is ok but not great but if I turn 2 channels on at same time the crt goes very dim to the state where you need to turn off lights and squint to see it am new to problem solving I have the schematics but its abit double Dutch .The curser tracker is dim no matter what the settings are.I have tried probing to see any power drops when both channels are on ,also if I increase divisions it dims with each down stepany help would be appreciated ,haven't got funds to replace not sure to strip and bin if cant fixRegards

author: true
author_rank: Frequent Contributor
timestamp: December 15, 2013, 04:55:25 am
content: If in doubt, check voltagesProbably a bad cap or damaged component, there isn't much to these scopes IIRC
Hitachi VC-750.Is it worth it? - Page 1
Forum section: electronics / beginners

author: shobo
author_rank: Regular Contributor
timestamp: April 22, 2017, 11:35:06 pm
content: i found on a local version of Ebay in Romania a Hitachi VC-7504.the guy asks for about 300$.is it worth buying as a beginner scope?

author: ebclr
author_rank: Super Contributor
timestamp: April 23, 2017, 01:42:08 am
content: Hitachi is a good brand, butTo much money for Real-time sampling: DC to 25MHzAny new 300 USD scope will do better for less
HM 507 connectivity problems - Page 1
Forum section: electronics / beginners

author: Balazs
author_rank: Contributor
timestamp: September 03, 2015, 07:29:57 am
content: Hello.I have problems connecting my Hameg HM 507 to the PC. (I'd like to copy some waveforms to a project...)I tried to connect it with a RS-232 to USB converter cable, I set the COM port for the required parameters and the software simply can't find the device.Anyone got experiences on this?
HM10 (3.6-6V) on 3.3V power supply - Page 1
Forum section: electronics / beginners

author: lutkeveld
author_rank: Regular Contributor
timestamp: January 08, 2019, 04:08:41 pm
content: I have no 5V source available, only a serial header with 3.3V powerWould it be possible to run the HM10 on 3.3V?All boards on ebay seem to have an LDO on board, because the bare module works on 3.3V.If it is really necessary I guess the LDO can be bypassed.Can I run the HM-10 BT module on 3.3V without issues?
HM310T clock running fast - Page 1
Forum section: electronics / beginners

author: Antuan
author_rank: Newbie
timestamp: April 25, 2022, 01:47:33 pm
content: Hi all,Newbie here, a programmer from Spain learning some electronics.Just picked up a HANMATEK HM310T from Amazon. Lots of interesting features there for me there, specially the memory for predefined outputs.Works nicely, except one thing: this model has a timer/counter, which starts counting in seconds when you switch on the output. I noticed that it is running faster than it should, and I'm not sure why. See a video here:https://imgur.com/a/hzxpSm1.Am I doing something wrong or shall I return it?Thanks!
Hobby Robot - Power requirments + Charging - Page 1
Forum section: electronics / beginners

author: iansmiler
author_rank: Newbie
timestamp: September 21, 2024, 06:02:04 pm
content: Hello,I have a hobby robot that I built which is currently powered from 4 x Ni-MH batteries @ 2000Mah per battery. I have to remove the batteries from the robot to charge them.I would like to switch to Lipo power but I do not know where to start... The robot's brain is a raspberry pi zero, and it has two wheel drive motors that operate through a L298n motor driver.Any help with speccing what I need would be greatly appreciatedIan

author: glebkooo
author_rank: Contributor
timestamp: September 21, 2024, 08:40:31 pm
content: Hi Ian,(newbie here)It is hard to say what is the total power requirement for your robot without info about motors and the voltage of a single Ni-MH battery you use.However, I would start with the following.Two 18650 Li-ion batteries connected in series will give you a voltage between 6V and 8.4V. That should be enough for powering motors, however, buck converter might be needed.For powering RPI Zero you would definitely need a buck converter capable of delivering 5V 1.5A. There are plenty of such DC-DC buck converter modules, just peek one that suits the RPI power requirement.I would use a module based on TP5100 IC for charging. It can handle two 3.7V Li-ion batteries connected in series.For powering that module you might use a USB charger with PD / QC function that can provide 12V, and a PD trigger module, based on CH224K, for example.
hold off and delay controls difference - Page 1
Forum section: electronics / beginners

author: Dan Moos
author_rank: Frequent Contributor
timestamp: July 02, 2016, 04:23:13 am
content: On my Tektronix 2213, as with many analog scopes, I have both a hold off control, and a delayed sweep control. To me they seem like just two different versions of the same end result.Besides how you actually set then up, what is the difference between the two things, and what makes one more preferable in a given instance?

author: AndyC_772
author_rank: Super Contributor
timestamp: July 02, 2016, 09:37:09 am
content: Delayed sweep means 'after each trigger event, wait a while, then sweep the display'. After each sweep, the scope starts looking for a new trigger event straight away. This mode is useful if you have a trigger which occurs some time before the part of the signal you want to examine.Hold-off means 'after each trigger event, sweep the display, but wait a while before looking for the next trigger event'. This mode is useful if you have a signal which contains bursts of activity separated by periods of inactivity. If you set the hold-off to be a value which is longer than the duration of the burst but shorter than the gap, then you'll get a stable display.Hold-off achieves this by ensuring you always trigger on the first event in the burst, after all but the very first trigger. The first trigger could happen on any event within the burst, but it's guaranteed not to trigger again until after the burst has finished. The trigger circuit re-arms at some point in time during the quiet interval, and so the next trigger is guaranteed to be the first event in the next burst.

author: Dan Moos
author_rank: Frequent Contributor
timestamp: July 02, 2016, 05:03:34 pm
content: Perfect explanation! I understood hold off, but couldn't see what made delayed sweep different. Note I do. Thanks!
Hole sizes for packages in an EDA - Page 1
Forum section: electronics / beginners

author: jrozner
author_rank: Contributor
timestamp: March 20, 2017, 06:17:32 am
content: When creating packages for parts in an EDA should the holes be slightly larger than the pin size in the documentation to allow for any tolerance in the manufacturing and to allow the pin to not be the exact same size? If so, is there a good general rule about how much larger to make it?

author: ElektronikLabor
author_rank: Regular Contributor
timestamp: March 20, 2017, 07:21:49 am
content: Yes, slightly bigger hole sizes for THT components are recommended.How much bigged depends on the size of the pin. For example: I use holes that are twice as big as the leads for small electrolytic capacitors, because of their thin leads.Fot bigger leads as TO-220 packages I use 20% - 30% bigger holes.For really big leads maybe 10% bigger hole.But it's my personal preferences. I believe that the next one will have different biases

author: Fire Doger
author_rank: Regular Contributor
timestamp: March 20, 2017, 07:56:11 am
content: It's good to have big holes, if you are using THT I assume that you are not really tight in layout so 0.2mm diameter more won't cause any troubles. I like tight holes but better safe than sorry.Every lead has tolerance in data sheet, fab house too so take for example worst case scenario both for component and PCB, go up to the next (or more) standard bit size and you are good.Also try to keep the same hole sizes.This may give you the ability to fab it an a low cost CNC (or home?) which cannot handle 20 different bit sizes.You can practice on that with some bits from eBay and scrap boards or download some libraries to see what most of them uses.If you are inexperienced it's good to test blocks of the board as small modules in diy PCB before manufacturing so this will give you an Idea if the footprints needs rework

author: mariush
author_rank: Super Contributor
timestamp: March 20, 2017, 08:51:27 am
content: I'd also add : round those diameters to values that are most likely to be supported by pcb manufacturers.For example, here's what Eurocircuits recommends :http://www.eurocircuits.com/PCB-design-guidelines/#holesQuoteand so on...Plenty of good advice in that document.
Holy smoke! - Page 1
Forum section: electronics / beginners

author: najrao
author_rank: Regular Contributor
timestamp: August 13, 2019, 08:22:43 am
content: Has gone downstairs for coffee, and returned to my work room. Was about to quit this too, but chanced to glance at a frightful fire on the wall just a metre away. Turned off the big 20A double pole switch adjacent, and blew out the smoky flame.What went up literally in smoke was a creation of mine of some five years ago. It has -- had -- a time interval set relay to turn off the electric heater in the solar tank. This contraption was a device I had made up to prevent a forgotten heater-on from running up huge bills.That it could have happened another time and gone unnoticed is what shakes the sh*t out of me. There was no high current, and none of the three overcurrent breakers upstream took cognizance.Yes, it was a Rifa X2 capacitor. To think Rifa was my sole choice for X2 when I was a designer at our electronics manufacturing unit! There must be tens of thousands of them I have seeded all over the country.You can never be too careful with mains electricity.

author: NaxFM
author_rank: Regular Contributor
timestamp: August 13, 2019, 08:27:54 am
content: I remember those infamous capacitors from Dave's teardown...Guess I'm right to spend a few euros to replace all the "dangerous" capacitors in old products...Edit:Wow, that was really a catastrophic failure, there was nothing flammable near it, so maybe, apart the burnt wall, nothing bad would have happened, I guess.But I reckon that a big uncontrolled flame in your house must not have been a very pleasant experience...That demonstrates perfectly the importance of compliant flame retardant electrical sockets
Home Lab Power Supply Ripple Spec - Page 1
Forum section: electronics / beginners

author: agsnow
author_rank: Newbie
timestamp: March 06, 2021, 12:59:15 pm
content: Hello All,A couple days after I ordered a RD6006 (100mVpp ripple spec) Riden can out with the RD6006P (20mVpp ripple spec). The questions is, in a home lab environment when does ripple become important and what levels are considered expectable?As of today I'm working on mostly micro controllers (RPi, ESP8266, PIC, Arduino...) and audio signals.Thanks for the feedback.

author: Vovk_Z
author_rank: Super Contributor
timestamp: March 06, 2021, 01:17:27 pm
content: "P"-version is a bit improved one (I guess not very much). But they are both DC-DC type so have quite a large common-mode noise. So they both possibly can be noisy in a real application (or not). It depends on a circuit sensivity and on our skill to manage with a common-mode noise. And so both definitely will improve a skill to manage with a common-mode noise.My answer to the question - 'It depends'As for me, I have a need for such a power supply, but a more powerful one (15-20 A), I have a use for it (whatever ripple it has).For ultra-low-noise circuits (they are usually low-consumption ones) I use another, an additional, or its own (linear) power supply (with 50/60 Hz transformer).

author: Cliff Matthews
author_rank: Unknown
timestamp: March 06, 2021, 11:20:06 pm
content: RD6006P has it's own thread now, and UniSoft will post FW updates there (see ripple tests, pics and draft pdf schematic).https://www.eevblog.com/forum/testgear/ruideng-riden-rd6006p-dc-power-supply/
home made flux - Page 1
Forum section: electronics / beginners

author: Deathwish
author_rank: Unknown
timestamp: August 03, 2015, 04:29:40 pm
content: I got fed up of buying liquid flux so made my own. 60ml of IPA and 6 or 4 grams of rosin.I found that printer refill kits with the 3 bottles and a syringe are really handy to store and dispense it with are cool too. Easy neat storage when your printer runs out of ink and free.

author: SeanB
author_rank: Super Contributor
timestamp: August 03, 2015, 09:10:15 pm
content: I just bought a 1l bottle of it and 2 dozen 50ml polyprop dropper bottles. Helps that I go there to collect orders for bottles at work, they also sell in small quantities, plus I also bought a Consol solar jar.
Home Protection Circuit 220VAC 50Hz - Page 1
Forum section: electronics / beginners

author: MMDuino
author_rank: Regular Contributor
timestamp: May 11, 2015, 11:31:12 am
content: Dear allplease see my circuit and advice if i can make it more easy.

author: jeroen79
author_rank: Frequent Contributor
timestamp: May 11, 2015, 09:21:53 pm
content: Can you explain what it should do and how it works?A quick observation:Why use D2 and D6 in series?