HP 54601A 100MHz Oscilloscope Teardown - Page 1
Forum section: electronics / testgear

author: balu
author_rank: Regular Contributor
timestamp: July 21, 2014, 08:30:23 am
content: Hi Eevblog’er,I have made a tiny teardown of my HP 54601A 100MHz oscilloscope to find out the production date of the Delas DS1220A non-volatile SRAM. And yes, I have a battery lifetime issue and must replace the SRAM (or battery) in the near future. It is an absolutely easy to use gadget and I will use this scope in future too.

author: balu
author_rank: Regular Contributor
timestamp: July 21, 2014, 08:33:28 am
content: And some photos of the screen with some menu functions displayed.

author: mskobier
author_rank: Regular Contributor
timestamp: March 13, 2015, 03:49:53 am
content: Balu,I recently came into possession of the same model oscilloscope. I agree, one of the simplest scopes I have ever operated. Push the auto button turn on the cursers and the scope does the rest. According to the boot screen, it is a 1992 model. Does this oscilloscope suffer from the same problem that the Tektronix 24xxB series does if the battery in the Dallas NVRAM dies, you loose all of the calibration settings and must go through a lengthy recalibration to be able to use it again? Mine currently works fine, but I am already in the process of replacing the NVRAM in the Tektronix 2445B, so should be able to remove/read/program and reinstall this chip fairly easily.ThanksMitch

author: Firebird00
author_rank: Contributor
timestamp: March 02, 2017, 01:25:27 am
content: Hi.I know this post is too old, but I need some help with this scope, so maybe you can help ?I have the same unit 54601a for some time, and one day I get the "Checksum error" message on the screen. After that day the scope did not worked anymore.I've changed the NVRAM and put a socket to make a easy job in the future. The scope now don't show errors but the channels (all 4) stopped working. When I put a signal in any of the four channels I get always the same message "No signal found".I see the signal in the screen but can not be triggered, the signal don't stop, Tried all the possibillities with the trigger menu, nothing changes.I think that this scope lost the calibration. I tried to do a Default calibration procedure many times but always I get a Hysteresys Error in one of the calibration steps and the calibration procedure ends without complete the process.I saw in this post that you wanted to make a backup of the NVRAM to prevent the same problem I have, so I want to ask you if it's posible you send me a copy of that file, that allows me to burn another (or the same) DS1220 and with luck this scope will work again.I'm asking that because is too difficult to find people with that scope, and more difficult people that wants to share information like a Dump of the NVRAM.Thanks in advance.

author: Deckert
author_rank: Regular Contributor
timestamp: March 02, 2017, 01:31:47 pm
content: Did you try to load calibration defaults?From the HP Service manual:1. Check the rear panel DC CALIBRATOR output level.If you are not sure how to check the DC CALIBRATOR, see "To check the output of the DC CALIBRATOR," on page 4–6.2. Load the default calibration factors.a. Set the rear-panel CALIBRATION switch to UNPROTECTED (up position).b. PressPrint/Utility , then press the Self Cal Menu softkey.c. Press the Load Defaults softkey.Manual available here:http://www.cube.co.za/~tva/workbench/hp54602b/HP-54602B-Oscilloscope.pdfIt covers the series.--deckert

author: SingedFingers
author_rank: Frequent Contributor
timestamp: March 02, 2017, 02:03:35 pm
content: Also schematics here for that unit:https://archive.org/details/hp_54601A_SchematicsBeen after one of these for a while as they're a step up from an analogue but not too far into digital territory.

author: Firebird00
author_rank: Contributor
timestamp: March 02, 2017, 07:08:49 pm
content: Thanks for your replies.Yes, I do the Self calibration a lot of times, but always I get a Failed error in the Trigger Hysteresis point, and aborts the calibration process, so the scope still uncalibrated. For the calibration I'm using an RG58 (50 Ohms) cable with two BNC, connecting one end to the back (calibration point) of the scope and the other end to the channel that the scope asks, first the 3, 1, 4 and the #2.Also I've downloaded the SM and schematics, and traced the signal applied until it arrives to Analog MUX 1 and also THold 1 IC's (on the block diagram), after that I don't know what to see, too many digital things for my knowledge.

author: balu
author_rank: Regular Contributor
timestamp: March 03, 2017, 06:23:04 pm
content: Hello Firebird00,I will upload (needs one or two days to be avilable) the NVRAM images as .bin and .hex files to this web site:http://www.ko4bb.com/getsimple/index.php?id=manualsI think you will find the ZIP file with the NVRAM image files at:http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=HP_Agilent/HP_54601_Digital_Storage_OscilloscopeI replaced the old NVRAM and make a copy of the content. I have hat no problem after the replacement with a new NVRAM.I hope the copy of the NVRAM will help

author: Firebird00
author_rank: Contributor
timestamp: March 03, 2017, 07:57:04 pm
content: Thank a lot Balu.I'll wait for that images,... Not sure if that will solve the problem of my scope, but I lost nothing trying, who knows?Also, I already have the same schematics you uploaded, from 54600 2 channels scopes. Basically are the same scopes, and at least we have more than nothing.Did you do the Self Calibration after the nvram swap? I suspect that when I do the self calibration and fails in Hysteresis point, it's because no signal is detected by the Trigger Hold IC, but I'm in doubt if I'm using a correct coax cable for that purpose. I'm using the RG58C/U that is not too bad, but I'm not sure if a not-too-bad coax cable can produce fails like that...Another question is what nvram did you put, the new one? I put the DS1220AB-120. I'm sure this one is so far faster tan the original one, but my doubt is with the numbers at bottom of the IC, it shows0031D097434. I suspect that the 0031D is the manufacture date, Year 2000 week 31, is it? If that is correct, then I buyed an 16 years old IC ? If so, then I have to buy a new and fresh nvram.Be continued...

author: balu
author_rank: Regular Contributor
timestamp: March 04, 2017, 09:36:52 am
content: Hello Firebird00,There was no need to use the self calibrtaion after replacing the NVRAM in my scope. Because I just copythe data from the old one into the new NVRAM. I can't find a new DS1220 in Germany and use the M48Z02-70PC1from ST. This NVRAM works fine in my scopeM48Z02 see:http://www.st.com/content/st_com/en/products/memories/nvram/zeropower/m48z02.html

author: balu
author_rank: Regular Contributor
timestamp: March 04, 2017, 09:41:49 am
content: Hello Firebird00,Attached to this replay you will find the NVRAM image file as .bin and .hex file as part of the ZIPI use the TL866CS Universal Programmer to read the data from the old NVRAM and program the new one.I hope after updated your NVRAM the scope will work

author: Firebird00
author_rank: Contributor
timestamp: March 04, 2017, 11:35:14 am
content: Quote from: balu on March 04, 2017, 09:36:52 amOk Balu. That's sound logical, you didn't loss your calibration data like me.I've found the original DS1220AB-XXX in Mouserhttp://eu.mouser.com/Search/Refine.aspx?Keyword=ds1220So I think I would preffer to buy the same reference as the original. I'll do that and tell what happens

author: Firebird00
author_rank: Contributor
timestamp: March 04, 2017, 11:41:35 am
content: Quote from: balu on March 04, 2017, 09:41:49 amThank you very much Balu.I saw in Amazon and EBay some of these programmers. I think that the most simple (without additional sockets) will serve for my purpose, because the DS1220 will fit directly to the programmer, without need for aditional or converting sockets, is that correct?

author: balu
author_rank: Regular Contributor
timestamp: March 04, 2017, 01:13:57 pm
content: Hello Firebird00,You can use the M48Z02-70PC1 as a replacement for the DS1220. The M48Z02 is cheaper and based on the datasheet from ST: "The M48Z02/12 ZEROPOWER® RAM is a 2 K x 8 non-volatile static RAM which is pin and function compatible with the DS1220.".I have hat no problem to read the old DS1220 and program the new M48Z02 with TL866CS Universal Programmer (no need for a adapter)

author: Firebird00
author_rank: Contributor
timestamp: March 05, 2017, 12:28:20 pm
content: Quote from: balu on March 04, 2017, 01:13:57 pmHi Balu.Bought today in Amazon the same programmer as yours, TL866CS, It will arrive between March 23 and April 1. Price is 56,99 Euro and come with 4 adapters. The price of the same without adapters is 51,80 + 4,87 for shipping, so for 32 cents of euro more I have 4 adapters, not bad uh?I will try to write the nvram I have here, if this don't work or have any issue then I will buy a new oneAt this point I have to wait until the programmer arrives, and continue working on this scopeI will post the news.Thanks a lot

author: Firebird00
author_rank: Contributor
timestamp: March 27, 2017, 11:41:49 pm
content: Hi.I've received the programmer today, burn the file you sent (both HEX and BIN) to the nvram and the problem still there, no trigger at all.Tried again the calibration process and it fails in the Trigger Histeresys point. I can see the signal apllied on any channel on the screen, but no trigger, also pressing Autoset I get always the same message "No signal found" on all four channels.Seems that the signal applied is lost in any point of the board, before the trigger, but arrives to other parts that can be processed and showed in the screen.I've removed and put back the socket of the nvram again, to discard any issue with bad solder point.All the functions and buttons works (vertical, horizontal, trigger modes, etc.)All setting remains there when power off and on again, so seems the new (old) nvram I have is not bad.Any help will be welcome.Thanks Balu for all your effort helping me with that problem.

author: JFJ
author_rank: Regular Contributor
timestamp: March 28, 2017, 01:50:16 pm
content: Quote from: Firebird00 on March 27, 2017, 11:41:49 pmI had the same problem and error message with a HP 54600B. I traced the fault to a failed TL071 Op Amp that's used to buffer the output from the trigger source multiplexers. The TL071 is marked as U43 in the trigger schematic (section 6 of the 54601A CLIP package).In the absence of any input signal to the oscilloscope, the voltages on pins 2, 3 and 6*of U43 should all be close to zero, with respect ground. My TL071 had failed with its output (pin 6*) stuck at the positive rail voltage.If your U43 is good, then check U12.1 (AD96687 Ultrafast Comparator). It compares signals from U43 and a DAC (which sets the trigger level), to produce a stable trigger signal.(*Corrected pin number).

author: Firebird00
author_rank: Contributor
timestamp: March 28, 2017, 09:13:18 pm
content: JFJ, I've read these voltages on U43:Pin 2 -> +4,28VPin 3 -> +4,87VPin 5 -> -4,84VNo signal applied on channels, and loaded Default Setup before taking measures.The schematics says the voltage on U9 pin 20 (AD9300 Multiplexer) should be zero, and I read +4,88. If this pin is the Multiplexer output, that goes to pin 3 of U43 trough R150 (10K), maybe the problem comes before U43? Voltage drop on R150 is about 4-5mV (+4,8752 -> +4,8708)What Do you think ?Thanks for your help.

author: JFJ
author_rank: Regular Contributor
timestamp: March 29, 2017, 02:40:12 pm
content: Quote from: Firebird00 on March 28, 2017, 09:13:18 pmSorry, I misread the output pin number from the schematic. It should be pin 6, not pin 5:U43 is configured as unity gain voltage follower - its output (pin6) is fed directly back to its inverting input (pin 2). So, the output voltage has to be the same as at pin 2 (4.28V). That voltage will drop to about 3.5V at the emitter of the common collector transistor (part of U15) that supplies the inverting input of U12.1.3.5V is far greater than the voltage that is applied to the non-inverting input of U12.1. Consequently, U12.1 can never switch to produce trigger signals.Quote from: Firebird00 on March 28, 2017, 09:13:18 pmIf the voltage is lower on the U43 side of R150, then source of the problem is likely to be before U43. In which case, a good place to start would be to check the voltage at test point 9:

author: Firebird00
author_rank: Contributor
timestamp: March 29, 2017, 06:14:12 pm
content: Looking today on the schematics I saw the mistake of pin 5 and 6 of U43. As you said, I have the same voltage on pin 6 and pin 2 of U43.Now I'm working on it, trying to find the source of the problem.TP9 is the output of U9 pin 20, and I have there +4,88V, as I wrote yesterdayQuote from: Firebird00 on March 28, 2017, 09:13:18 pmI have zero volts on the inputs of U9, pins 3, 5, 8 and 10, +4,88V on pin 20 (Output) and +7,0V on pin 19 (Bypass)Yes, the voltage un U43 side of R150 is lower, some millivolts.Also, next to TP9 is C58 (0.01uF) capacitor. I have +4,85V on both sides of that capacitor. If capacitors blocks DC voltages I don't understand why I have these reads, maybe that capacitor is bad also, or is the main problem?Thanks

author: JFJ
author_rank: Regular Contributor
timestamp: March 29, 2017, 08:16:29 pm
content: Quote from: Firebird00 on March 29, 2017, 06:14:12 pmOops! Preoccupied with my first mistake, I made another (award self zero points for observation).Quote from: Firebird00 on March 29, 2017, 06:14:12 pmThe voltage on both sides of C58 will be the same when the trigger is DC coupled. That's because C58 - the AC trigger coupling capacitor - is shorted-out by pins 14 and 15 of U10 (DG211 - Quad Analogue Switch), when DC coupling is selected.If you change the trigger coupling to AC then the U10 switch should open, and C58 will be the only connection between TP9 and R150. That may allow you to determine which side of C58 is connected to the source of the 4.85V.

author: Firebird00
author_rank: Contributor
timestamp: March 29, 2017, 08:40:08 pm
content: Quote from: JFJ on March 29, 2017, 08:16:29 pmDont worry about the mistakes. You are doing a good job helping people (like me) and that is the most important thing.I switched the trigger from DC to AC, and now I have +4,88V only on the U9 (pin 20) side of C58, and also I have close to zero volts on U43 (OP amp) pins 2,3 and 6, is that correct?.That information tells you something good? I'm starting to think the U9 is the source of my problem, but I'm waiting for your veredictThank you a lot.

author: JFJ
author_rank: Regular Contributor
timestamp: March 29, 2017, 09:53:37 pm
content: Quote from: Firebird00 on March 29, 2017, 08:40:08 pmYes. Only an AC signal can pass through C58 to U43. Whatever voltage is applied to the non-inverting input of U43 will be replicated on its output. It couldn't quite achieve that when 4.87V was applied, because it was too close to the +5V supply rail.Quote from: Firebird00 on March 29, 2017, 08:40:08 pmYou have already established that the four inputs to U9 are at zero volts. So, unless U10 is leaking its +5V supply to pin 15, U9 has to be the prime suspect.One way of determining whether it is U9 or U10 that is faulty, would to remove the interconnecting resistor (R196). Though, you might be able to achieve the same thing, without removing R196, if you can measure a voltage difference on either side of the resistor (the highest side points to the faulty chip).

author: Firebird00
author_rank: Contributor
timestamp: March 29, 2017, 10:23:05 pm
content: Ok.I took this measures without removing R196. I don't have experience yet removing with SMD components.I had to switch the trigger coupling back from AC to DC because the less significants digits of the DMM didn't stop moving, then with trigger in DC mode I have read on R196 on the pin that points to U9 about 2-4mV more than the pin looking at U10, that is +4.9042V to U10 vs +4,9056 to U9If the faulty chip is U9, then I will call a good friend to do the swap for me...but meanwhile I can do some research...So I think your veredict will be to replace U9 ?Thank you.Update today March 30: I've ordered a new AD9300KP from the USA. With luck I will receive it in less than two weeks. I will replace it and see what happens.Another question I have, what do you think about the +7,0V on U9 pin 19, multiplexer bypass? Is that correct or is bad also like the 4,8V in the output pin 20?

author: JFJ
author_rank: Regular Contributor
timestamp: April 06, 2017, 07:35:51 pm
content: Quote from: Firebird00 on March 29, 2017, 10:23:05 pmThat appears to be correct. The voltage on pin 19 of my U9 multiplexer is +6.9V.Quote from: Firebird00 on March 29, 2017, 10:23:05 pmIf you want to be absolutely certain that U9 is faulty - without un-soldering any components - then you might consider cutting pin 20 of its PLCC package. That would, obviously, completely isolate the multiplexer's output, but it could be reversed with a blob of solder. Cutting the PLCC pin high up should eliminate most of the risk of damaging the PCB. However, you would need a very fine and sharp pair of side cutters.As a bonus, isolating the U9 output would allow you to check the trigger circuitry at U43 and beyond. The 'Line' trigger signal is not multiplexed by U9. So, if all is good from U43 onward, selecting 'Line' as the trigger source, setting the time-base to 5ms/div and a channel to around 1V/div, you should be able to display a stable/triggered sinusoidal waveform (the mains power signal that's picked-up by your body) by simply touching the probe tip with your finger.BTW, I'm sorry not to have responded sooner, but recent security upgrades to this forum's server prevented me from posting. I still prefer to use an old Windows XP PC for connecting to the Internet. The version of Chrome that still supports XP, isn't compatible with the SSL/TLS protocols that are used to provide secure connections to EEVblog pages. I was about to install a current version Firefox (which does still support XP), when I noticed that the http/https redirect problem had been corrected:https://www.eevblog.com/forum/news/server-ssl-upgrade/msg1178017/#msg1178017My old PC lives to fight another day

author: Firebird00
author_rank: Contributor
timestamp: April 06, 2017, 09:55:58 pm
content: Hi JFJ.Thanks for your help, I appreciate it too much.I'm computers technician and I understand your problem. I too preffer Windows XP, but unfortunately it doesn't work in these days (if you want to navigate on internet...)Your suggestions arrives a little bit late because yesterday I have removed the U9 IC myself (looking some videos of smd removal procedures before do the job). I bought a good tool that helped me a lot to do that, Chip Quik SMD1. With that thing I've removed the IC easily without damaging the board.Now the scope is waiting for the new AD9300KP to arrive, so lets see what happens when the IC is here on place, I cross my fingers... I suppose the new IC will arrive in the next week.I do some readings with the IC removed, and where I had +4,8V on U9 pin 20 now I have zero volts, also pin 19 is zero volts, I suppose it's normal because U9 is missing...One thing that I dont understand is why now I have zero volts on both sides of capacitor C58 when trigger is DC coupled, I tough I will see +5V on the U10 side of C58, and zero volts on the U9 side. Maybe U10 needs some signal to work that came from U9, and of course, without U9 then no signal to U10 then zero Volts on C58.If you want I take some readings ask me, I do it with pleasure.Regards.

author: JFJ
author_rank: Regular Contributor
timestamp: April 07, 2017, 12:05:31 pm
content: Quote from: Firebird00 on April 06, 2017, 09:55:58 pmWith the trigger set to DC coupling, the TRACDC (Trigger AC/DC) control line is at logic 0. That line is connected to pin 16 of U10, and controls the state of the analogue switch that is between pins 14 and 15 of U10. A low on pin 16 closes the analogue switch, which connects both sides of C58 together. Hence, the voltage on both sides of C58 has to be the same.When AC trigger coupling is selected, TRACDC goes high - causing the analogue switch to open. That removes the direct current path between the U9 output and the U43 input (leaving only the AC path through C58).Quote from: Firebird00 on April 06, 2017, 09:55:58 pmAs U9 is now removed, you could try the Line trigger check that I suggested in my previous post. The Line trigger doesn't use U9, but does use the trigger circuitry that follows. If Line triggering works, then it should be safe to uncross your fingers.NB The datasheet for the AD9300KP carries an ESD warning:Taking precautions against ESD is worthwhile. It would be a shame for your new AD9300KP to die prematurely, because it suffered an electrostatic discharge during installation.

author: Firebird00
author_rank: Contributor
timestamp: April 07, 2017, 04:48:37 pm
content: My good friends Balu and JFJ. I'm glad to tell you that my scope is working again !!Balu, I didn't forgot your helpI've received today the IC's, soldered it (no too bad for my first time soldering SMD's), and it's working again.Alll channels are working, and the self calibration goes to the end, finalizing successfullyBefore I get Trigger Hysteresis fail all the times.I'm VERY VERY happy and want to thank you both you JFJ and Balu, for your help, you gave me a very happy weekendI bought a pack of 5 Multiplexer's from the USA, because I did not wanted to wait more tan a month to receive one IC, and maybe a fake IC from China. I will keep one more with me as a backupand will sell the 3 remaining ones.Thank you again friends.

author: JFJ
author_rank: Regular Contributor
timestamp: April 07, 2017, 06:07:54 pm
content: Quote from: Firebird00 on April 07, 2017, 04:48:37 pmCongratulations, that's great news.Now might be a good time to think about possible causes of the failure. For your NVRAM to become corrupted at the exact same time that U9 failed is too much of a coincidence. It's hard to imagine how a small breakdown within U9 could have affected the NVRAM. Something external, such as a mains transient, may have caused both problems. If a power line transient was the likely cause, then protecting your test equipment with a surge-arrester could be advisable.

author: Firebird00
author_rank: Contributor
timestamp: April 07, 2017, 09:12:49 pm
content: Thank you JFJ.Yes, it's very strange what happened with that scope, two components in the same time seems is not a coincidence, as you said.Today I'm playing with it for about 5 hours or more, doing perfomance and calibration tests regarding the service manual and seems all is working ok, all measures are between the parameters.I get impressed that this scope can trigger a sinewave of 212 MHz !! UUhhhh, I've never do that before !! Of course there is a lot of attenuation but I can see the signal perfectly...Now I'm like a kid with new shoesI've never had line problems at home, or I think so, because none of my instruments was broken or showed issues, only that scope was the exception, but I looked that and the voltaje is ok, also ground line, without fluctuations.For now it's working, for some years I hope..., thanks to you and Balu.Regards

author: signal66
author_rank: Newbie
timestamp: September 06, 2017, 08:10:22 pm
content: Hello,many thanks for the information in this thread concerning reparing the HP 54601a.Many thanks to JFJ and Balu and also Firebird00.I got one defect device with vertically streched display image and dead nvram. No trigering possible.O.K., as many explanations here, I desolder the nvram, I put a new socket and I installed a newM48Z02-70PC1 from ST. After powering on the old man he started perfectly. Load defaults and readyfor working. Fine.Concerning the display I put a new C609 (1000 uF) and a new C608 (10uF , 16V) and the display worksnow fine.My question: I will copy the old nvram and I want try to write the image file to the new nvram.I this really necessary or it is enough to work with the default data ?

author: balu
author_rank: Regular Contributor
timestamp: September 07, 2017, 07:21:46 pm
content: Hello signal66,I’m not sure, but I think the default values are used after production to make the scope working and a calibration is needed for the correct values. The question is - what are the size, range differences between default values and possible calibration values for compensation purposes. My recommendation is to use the last (or old) values from the copy of the NVRAM, if possible.

author: signal66
author_rank: Newbie
timestamp: September 08, 2017, 07:00:36 am
content: I got a programmer and I tried to copy the nvram data from the old nvram.When I install the new nvram with the old data the device tells that the calibrationfor the vertical is wrong. No idea why.O.K., I decided to load the default on the new nvram again and forget the old data.I remark that the signal amplitude of channel 1 and 2 is not accurate, but channel 3and 4 are fine. For example if I insert a sinus signal with 1Vpp at 100kHZ in channel 1,then the measurement shows 0,83Vpp (I think the impedance matching is O.K).O.K. I run the calibration as explained in the service documentation. Then the mentionedproblem should be solved with this calibration.The vertical calibration was fine and passed all things.For the delay calibration the service manual says to apply a pulse generator with less than5ns rise/fall pulse. I tryed this with a low bugget siglent generator with 7ns rise/fall pulse.Then the delay calibration seamed to work fine and passed all things.I test again the amplitude of the sinus signal and the Vpp display showed the accurate valueat all channels.O.K. all seams to be fine now and the old man is working again for some years. Nice deviceand engineering work.Again, many thanks here to all.

author: JFJ
author_rank: Regular Contributor
timestamp: September 08, 2017, 10:13:55 pm
content: Quote from: signal66 on September 08, 2017, 07:00:36 amYou could improve your generator's rise/fall time by passing its output through an external advanced CMOS logic gate or an ultra high speed comparator, like the one used here:http://www.starlino.com/build-a-really-fast-pulse-generator-50ps-rise-time-using-an-ultra-fast-sige-comparator.htmlHowever, the service manual specifies that the amplitude of the calibration signal should be 500mV peak-to-peak. So, something like this circuit (which enables the high and low signal levels to be set) might be more appropriate:https://www.maximintegrated.com/en/app-notes/index.mvp/id/1866

author: signal66
author_rank: Newbie
timestamp: September 09, 2017, 06:10:55 pm
content: Hello JFJ,sorry, I modified my last reply instead of doing a new one.But the question about the pulse generation with less than 5nsrise is still important for me. So, in that way it is nice to read youranswer about the simple solution using the max6644. I will try this.The max6644 is available.

author: JFJ
author_rank: Regular Contributor
timestamp: September 09, 2017, 10:59:25 pm
content: Quote from: signal66 on September 09, 2017, 06:10:55 pmHello signal66,The application note circuit diagram appears to contain typing errors (theMAX6644is a fan speed controller). I believe that the analogue switches should have been marked asMAX4644.

author: signal66
author_rank: Newbie
timestamp: September 10, 2017, 11:57:13 am
content: Hello JFJ,your are right. I remark also this, but I wrote it also wrong.The part is actually sold by Conrad in Germany and the priceis under 5EUR, this is for trying O.K. It is a smd part.On the other side I am wondering, when I am looking for fastpulse circuits mostly is no Information about rise and fall timing,but I think pulse width under 10ns should be enough for thecalibration.