I swear we share a mind. I’ve started replicating your DC Load Project and I stopped because I started rebuilding the DROK 900W boost converter I have. I was playing with it and blew the micro so I programmed an Arduino to send the output signal to the switcher, monitor the load, and display the info to a 20x4 LCD using the U8GLib. After watching your videos all day, I have some new ideas...one is to make all the PCBs and put the j to one Scullcom project box, a nice 19” OKW unit. Thank you for all your contributions and you inspire me to keep at it.

@scullcomhobbyelectronics1702

6 жыл бұрын

Its good to experiment but sometimes things happen. But that's how we all learn. Have fun! Regards, Louis

Great project videos!! As always... Please keep them coming, I learn so much just watching your though process and the complete circuit diagram walkthroughs you do... You're a natural educator.

@scullcomhobbyelectronics1702

9 жыл бұрын

+Kurt Petrucci Thanks for your kind comments.

Hello. Just recently subscribed, like your work. This reminds me of hacking my old Circuit Specialties bench supply to make it more useful. (Adding a CC/CV LED, a lower current range, etc.) Fun, useful and a learning experience. I like your output switch, and have use like circuits in a few places. One thing I noticed, tho, as I'm always using my power supplies for LEDs, battery charging and other low voltage, high current needs. As you set the DROK to lower voltage, you drop your gate drive on the FET. Looks like Vishay likes at least 3V G/S for that part, and for really low on resistance, more like 5V for good RDS on. With those two 100K resistors in the gate drive, you only get 1/2 the DROKs output voltage for drive. Suggest taking the 100K at the collector of the 2N3904 down to 4.7K 1/4W, this will give good turn-on down to 4-5V output, and still keep the zener and resistor current reasonable at a 40V output. At Lower than 5V, tho, is a bit trickier. You don't have much 5V current available from the onboard regulator at 30V input. Maybe add a separate regulator, (12V , if your input is always 15V or higher, or 5V) add a low current draw relay in place of the FET, and change the base resistor of your 2N3904 to 1K. Relay + snubber diode from the collector to new 5V or 12V source. That won't care about the output voltage. Or do low side switching with an N-channel FET, a 100K back to the power input to turn the FET on, then use the 2N3904 to shunt it out as your OFF state. Only good, tho, if you're not using anything else in your system with a common ground to your power supply. Add that enabled LED, too! Just several thoughts. Keep on tweaking those electronics! DStuart. (40+ years electronic tech/hobbyist/tweaker)

I just love your bi-stable circuit starting at 9:15. Dave Jones had something similar with 3 transistors, that was an "Soft on-off switch" as well. I think it was on one of his power supply design videos. Not sure though. Please remind your viewers my pining a note on top, that they must ground all the unused inputs of the CD4069 or any other equivalent inverter IC (ie 74HC04, LS04,...etc), in order to minimize power consumption. A CD74HC04 for example, will consume ~22mA of quiescent current if all inputs are left floating in the breeze, but consumes under 1uA if all the inputs are grounded. That is a huge difference.

@ufohunter3688

6 жыл бұрын

Found the circuit I mentioned above; kzread.info/dash/bejne/eKOXm7RplKaYmaw.html

Another option to tin your PCB is there are several chemical tin plate solutions that works very well and tins the whole board to protect the copper and provide easy soldering. The solution can be used over and over so a small bottle lasts for years and years.

@scullcomhobbyelectronics1702

9 жыл бұрын

+Rambozo Clown Thanks for your comments. Yes you could use a chemical tin plate solution but this takes a lot longer to prepare the PCB before you can mount the components. I wanted to show the hobbyist a quick simple and cheap method. But thanks for mentioning the tin plate solution, which give them another alternative method.

I would also like to thank you for your great tutorials. Many Thanks.

@scullcomhobbyelectronics1702

6 жыл бұрын

Thanks your welcome. Regards, Louis

Fantastic. Lot's of great ideas that can be reused. Thanks!

Thanks for all the great videos.

Excellent tutorial as usual, thanks for sharing.

@scullcomhobbyelectronics1702

9 жыл бұрын

+Yann Kitson Thank you.

Thanks for doing this video/tutorial. I appriciate the amount of time an effort you put into doing this. With only 5,000 plus view to date it must give you some satisfaction that people like what you are doing. Excellent.

@scullcomhobbyelectronics1702

7 жыл бұрын

Thanks Joseph. I am happy to share my videos on my projects. Regards, Louis

Great video (as usual). A very fine mod. Keep on the nice work.

@scullcomhobbyelectronics1702

8 жыл бұрын

+Christian Christiansen Thank you. I am just uploading a new video at the moment.

Very nice! Thanks for sharing.

Very well made video. Thanks!

@scullcomhobbyelectronics1702

6 жыл бұрын

Thank you.

Excellent mod, thanks for sharing :-)

@scullcomhobbyelectronics1702

9 жыл бұрын

+Mark Garth Thanks Mark.

What a smashing mod to the drok, thankyou for making a video :-D. Thats so much nicer to be able to adjust the voltage before turning on :-) I like the ability to trim out slight errors, the fet will lose a tiny tiny amount of output voltage under the full load, but thats almost nothing so its irrelevant. Using a stable "gain block" i.c just cuts out all the problems with using op amps, just the accuracy of the sense resistor matters, nice and simple :-). Clever and simple design of the output switch, i really like that :-). I can see the output switch being used on larger supplys with a bank of parallel power fets to do the heavy work. Just one thing i would add, a tiny led to say when its enabled, i bet a resistor and low power led tacked on to the output of the hex ic would do that.

@scullcomhobbyelectronics1702

9 жыл бұрын

+zx8401ztv Thanks for you valued comments as always. Yes, agree you could simply add an LED to show when the output is enabled. There are 3 spare inverters in the 4069 chip which are currently not used - so we could use one to drive an LED.

@zx8401ztv

9 жыл бұрын

+Scullcom Hobby Electronics Yes i noticed the 3 unused inverters, i was thinking a simple add on without reworking the pcb. I did use a 4017 decade counter to select voltages for an eprom programmer, a simple button +resistors/capacitors fed the button into the 4017 clk input, and the outputs fed transistors that selected resistors in a Lm317 adjustable regulator, i had six voltages in order then i looped the reset pin to jump the 4017 to no 1 again. Simple circuits work really well :-D

@scullcomhobbyelectronics1702

8 жыл бұрын

+zx8401ztv Home made eprom programmer bring back memories!! I also build one in the 1970's to program 2716 and 2732 UV erasable eproms. That was in the days when I use to program 6502 processors in machine code. Things have move on a long way from those days !!!!

@zx8401ztv

8 жыл бұрын

+Scullcom Hobby Electronics True but im not sure if having eeproms in p.c's was such a clever idea, the old eproms didnt suffer with virus attacks and daft people wrongly updating there bios flash device. Simple days with less junk to go wrong :-D

it's great to see you etch your own pcb. next time could you perhaps make a video of your pcb process? do you use iron on transfer or photo expose? and demonstrate your etching procedure. your artwork came out nice and sharp for a self etched board.

@whitephosphorus3274

9 жыл бұрын

+thefamilyman he has already made very interesting videos about pcb etching with the same precision and educational value as most if not all of his videos.

@whitephosphorus3274

8 жыл бұрын

+thefamilyman you should also checkout Mr Carlson's Lab way of etching circuit boards, it's a bit different and less complicated as you don't need the photoresist step.

Great video as usual. I would love to see your take on a "from scratch" mini bench power supply with current limiting, short protection, etc. Wouldn't have to be high power device, just a great little learning exercise... Cheers.

@scullcomhobbyelectronics1702

9 жыл бұрын

+Leigh Robinson Thanks. A Mini Bench Power Supply would be a nice little project. I will have a look at doing one.

@gwilsonmail

9 жыл бұрын

+Scullcom Hobby Electronics I'd like to see that project. Great channel.

@leighrobinson

9 жыл бұрын

Scullcom Hobby Electronics Brilliant! Another thing I have been messing with recently (that you might comment on in the context of an oscilloscope tutorial) is building a little external trigger circuit for an old analogue scope that doesn't have delayed sweep or hold off. Do you have any advice on how that problem was handled before 'scopes had that feature?

@scullcomhobbyelectronics1702

8 жыл бұрын

+Leigh Robinson From memory hold-off and delayed sweep was introduced in the early 1970's. Adding an external trigger input to a old scope that did not have one should be fairly straight forward. You would need a switch to disable the internal trigger signal and instead connect that point through the switch to an external trigger BNC socket which you could fit. Simply doing this would allow you to still use the trigger level control and polarity switch + or _. You would need to get a copy of the scope schematic so you could trace the trigger signal circuit path.

@leighrobinson

8 жыл бұрын

Oh, I meant a circuit to produce the triggering signal, rather than adding an external trigger interface! I suppose it is a bit of a waste of time, but as a learning exercise I was thinking of trying to build something that adds hold off, etc by generating the trigger entirely separate from the scope. I am assuming a fast sawtooth generator would be a crude first attempt. This came about after realising that the analogue scope I was given is missing these critical features for complex waveform analysis, like digital pulse trains, etc. Though now you have mentioned schematics, I am thinking about possible modifications to the current trigger to delay the circuit. Unfortunately my skills are probably not up to that task, but this is all a learning exercise! Thanks for the input.

just another quick comment, you should trim under no load as there will be voltage drop in the cables going to the DC load. or use a multimeter at the PSU measuring the output voltage under load, don't use the DC load meter as it will have some voltage drop from the leads. but with only with one decimal place accuracy I guess it doesn't matter much.

@scullcomhobbyelectronics1702

9 жыл бұрын

+thefamilyman Thanks, a fair point. You are right with only one decimal place on the display it would have little effect.

Scullcom Hobby Electronics Thanks for another great mini project series. Could you please explain the function of the two 10k resistors, R17 & R18, across the output junction J2 ? Are they bleeder resistors for C3 and/or L1 ?

You have a very interesting channel and videos. I like your videos very much and you have a very educational way you present information. I wonder if you could not also create an electronics educational series with electronics basics and explanations of basic laws and components all playing with this sort of stuff should have basic understanding of.

@scullcomhobbyelectronics1702

9 жыл бұрын

+Majid Faraj Thanks for your comments. I did think of doing some basic electronic videos but I thought there are already quite a lot of you tube videos out there with this type of content. However, There may be a point of taking a different approach to basic electronic components and their applications. So I will give it some thought.

@whitephosphorus3274

8 жыл бұрын

+Scullcom Hobby Electronics Thanks, you have a way that reminds me of the teachers I liked in school =)

Sorry , didn't wait for the end of the show to see you have already linked in the artwork :)

@scullcomhobbyelectronics1702

8 жыл бұрын

+steve meacham No problem. Hope the PCB artwork is helpful.

Thumbs up!

@scullcomhobbyelectronics1702

8 жыл бұрын

+Dominik M Thanks.

Good project. What do you use for the close up video work ?

@scullcomhobbyelectronics1702

8 жыл бұрын

+netdudeuk Thanks. I just use the macro feature on my video camera.

Hello. Was wondering if you ever tried setting the DROK output to, say, 3.5V (led drive) or LIPO charge levels) and see how the output switch handles it? I brought this up in an earlier comment and wanted to see how it would work. Like your videos, and am thinking seriously about building the milliohm meter. Keep up the good work! Stu

@scullcomhobbyelectronics1702

8 жыл бұрын

+D. Stuart Thanks for your comments. Have not tried it but I think is should work.

Great add-on.. I've just ordered a unit myself.. Don't suppose you have spare PCB you could sell me, or maybe a JPEG scan of the track layout ?? Regards, Steve

Hi. I'm looking to power my Camcorder from RC Lipo batteries ( 3S1P / 11.1v / 3Cell ) so i can get much longer Record times. The camcorder has an external charge / PSU socket which allows me to record while running on mains power. My question is, how do I reduce the voltage down of the LiPo battery to DC 5.3v / 1.5A? Obviously I'm concerned about a stable & reliable device that won't spike of generally fry my camera! Your advice please?

Soft switch is fine, but dont think it will work properly at lower output voltage when the required Vgs may not reach to the point which could turn the MOSFET On.

@scullcomhobbyelectronics1702

8 жыл бұрын

+Satyajit Roy Thanks for your comments. The 'P' Channel Mosfet which I selected for this project was a Vishay SUD50P06 which has a VGS threshold voltage range from -1v to -3v. As the Drok does not operate below around 4 to 5v then the Mosfet should work fine for the normal operation of the Drok DC-DC converter.

Very good teacher evenings Skullcom Hobby are very interesting experiments you show us I'm Mexican and I've been following but has time i'm in a esperimento of creating hydrogen but I need a device to regulate the voltage to generate the hydrogen is not if you I could help this project because the rest already have but to put it in the car when going from low to high is not enough hydrogen and need some circuit for Realise that function do not know if you could help me please