Mystery of the Tattoo power supply? (+ Teardown Pg.2) - Page 1
Forum section: electronics / beginners

author: MrZwing
author_rank: Regular Contributor
timestamp: October 01, 2014, 09:42:41 am
content: HelloHas anyone looked inside a tattoo power supply?or doses anyone know the desired attributes for one?I have been thinking about building one for fun but I want to try to build something that can be considered a high-end is it as simple that it is just a nice lab supply with connections for a tattoo machine and a pedal?and to be honest my understanding of power supplies is at the moment limited since I'm still reading up to make my own bench lab supply.nut I see this as a nice challenge to build a really nice power supply for tattooing (have a friend that is a tattoo artist who only buy the cheap stuff) and maybe try to build a nice tattoo machine to learn more about coils and similar thing's. I learn a lot more by doing and some trial and error haha.

author: Rerouter
author_rank: Super Contributor
timestamp: October 01, 2014, 10:07:16 am
content: It really looks like most of them are just a variable voltage power supply. with the foot pedal forming the lower half of the feedback divider for the supplyTake a generic LM317 supply, on the lower feedback resistor parallel in a potentiometer foot pedal, and add some series resistance for the foot pedal connection to limit how high the voltage can go, if the foot pedal is not connected, the lower feedback resistor sets it to some safe voltage, if you have the foot pedal fully depressed the series resistor in the foot pedal lead limits how high the voltage can go, and your control range swings between these 2 points,

author: MrZwing
author_rank: Regular Contributor
timestamp: October 01, 2014, 12:48:49 pm
content: I found thisbut there is a even more stable regulator then L146 the L146CB.does this seem like something usable or is there some modern more efficient way to get a super stable power supply?

author: Rerouter
author_rank: Super Contributor
timestamp: October 01, 2014, 01:06:24 pm
content: With switch mode style power supplies you can get a greater efficiency than a standard linear supply like the one i suggested, however they are harder to make stable over a large output range, and are generally more electrically noisy,however i am assuming this supply powers the ink needle thingy, in which case electrical noise over 3 times its RPM likely wont worry it, and its own inertia will smooth out any sudden changes in the supply,so in reality you dont need in any large way a "super" stable supply, just one with say less than a few hundred mV ripple, and while i myself have no ideas on making a switcher with a wide output range, there are likely to be plenty of schematics out there that would fill your needs,If you really want it to be like a lab supply your going to have to bite the bullet with efficiency and stick with a linear supply, the LM431 is a chip i have seen used repeatably in circuits that have to cope with large step changes in load (I dont want to imagine what might cause a motor stall condition in tattoo-ing ) besides i would like to point out that the foot pedal will likely define how stable your circuit is, even when driving at a steady speed a persons foot will happily drift a few % of the throttle range,

author: MrZwing
author_rank: Regular Contributor
timestamp: October 01, 2014, 01:22:58 pm
content: Hmm well I see that I need to read up on power supply types.I'm the kind of guy that like to "over-kill" in several situations so i want a supply that gives a lot of stability so it will be a smooth ride for the tattoo machine.

author: katzohki
author_rank: Frequent Contributor
timestamp: October 01, 2014, 05:25:14 pm
content: I know that there are people in prison who can probably help you. I don't know anything about them, but I have a feeling they don't need to be particularly fancy.

author: KJDS
author_rank: Super Contributor
timestamp: October 01, 2014, 05:47:21 pm
content: There is absolutely no need for anything fancy, tattoo machines just need some volts and a little smoothing. Making it adjustable helps if you want to vary the speed.I suspect that the fancier you tried to make it, the more issues you'd run into from the back emf from the coils.

author: N2IXK
author_rank: Frequent Contributor
timestamp: October 01, 2014, 07:25:00 pm
content: Wouldn't the nature of the application (driving needles through the skin surface) seem to dictate a PSU that meets medical device standards, at least for leakage current?The units I have seen always seem to be the cheapest crap possible.

author: Bored@Work
author_rank: Super Contributor
timestamp: October 01, 2014, 08:58:28 pm
content: Quote from: N2IXK on October 01, 2014, 07:25:00 pmI don't think the "artists" who produce thishttp://failblog.cheezburger.com/ugliesttattoosgive a toss.

author: katzohki
author_rank: Frequent Contributor
timestamp: October 01, 2014, 09:10:34 pm
content: Quote from: N2IXK on October 01, 2014, 07:25:00 pmYeah, that's a good point. You would think that the "legit" ones should.

author: IconicPCB
author_rank: Super Contributor
timestamp: October 01, 2014, 09:47:57 pm
content: I used to make power supplies for a little Australian company ( whihc sadly went by the way of a lot of manufacturing companies in Australia; choked by the imported weeds ).There are two types of machines in use: a DC machine and an AC machine.Each requires a specific power supply configuration.AC machine as the name implies runs at twice the mains frequency and relies on a triac based phase control drive.OI implemented the DC option by hanging a bridge rectifier and filter network on the back of AC machine so that one power supply would handle both AC and DC machines.Made for a reduced inventory of parts having one PCB that handled both possibilities , only the front panel needed changes.

author: kc9qvl
author_rank: Regular Contributor
timestamp: October 01, 2014, 11:23:20 pm
content: Why wouldn't a tattoo machine use pwm instead of a mechanical contact? 3 Pots could control voltage, frequency, and duty cycle. Seems like that would offer a much degree of control.

author: Teledog
author_rank: Regular Contributor
timestamp: October 02, 2014, 03:41:18 am
content: I use Zhaoxin (cheap Chinese) variable power supplies. (part of the "lab")Voltage and current are adjustable 0-5 amps & 0-30Volts DC, the analogue is cheaper than the digital {not necessary}..They work really well with the tattoo guns..really!I only tattoo pork bellies though (for unusual smoked dinners..food grade food dyes)Check your local Asian electronics shop or eBay!

author: IconicPCB
author_rank: Super Contributor
timestamp: October 02, 2014, 04:03:12 am
content: Tried three pot solution.Clients got confused and went back to oldfashioned arcing contact DC machines and single pot control.

author: MrZwing
author_rank: Regular Contributor
timestamp: October 02, 2014, 06:10:31 am
content: Well I personally ain't going to tattoo anything, i have a friend that is a Certified Tattoo artist and I'm currently Teaching myself to build power supplies and building a tattoo power supply that he could judge the quality off was my thought.also thinking about learning about coils and things by building a a tattoo machine, I like the learn while I build stuff approach while I read and try to make something that is top of the line instead of just "it works" it's an OCD thing need to make its as good as I possibly can.well been thinking about buying a cheap as one to tear apart and see how it can be made better after I seen how it works./MrZwing

author: MrZwing
author_rank: Regular Contributor
timestamp: October 03, 2014, 05:37:47 pm
content: My tattooist friend had a cheap tattoo supply that i could tear apart.so I'm going to go through it and read up some more on power supplies but i think I'm getting somewhere.think ill build a standard lab supply for my other experiments and learn some more before i start building some more advanced types./MrZwing

author: katzohki
author_rank: Frequent Contributor
timestamp: October 03, 2014, 09:49:05 pm
content: Post the teardown here!

author: miguelvp
author_rank: Super Contributor
timestamp: October 04, 2014, 11:25:09 pm
content: Related, someone under the Repair section is trying to repair a global specialties 1310 power supply that came from a tattoo machine.https://www.eevblog.com/forum/repair/global-specialties-1310-power-supply/No pictures but maybe you can ask there for the OP to post some pictures.

author: Andy Watson
author_rank: Super Contributor
timestamp: October 04, 2014, 11:39:32 pm
content: Quote from: miguelvp on October 04, 2014, 11:25:09 pmYou can download the manual, which includes most of the schematics, from here:http://www.globalspecialties.com/test-equipment/power-supplies/item/3-1310.htmlIt's just the standard lab supply, i.e LM317 nailed into a box with a bridge rectifier, smoothing caps and a transformer - three times over in the case of the 1310. Looks like a reasonable quality build, but the fact that both of the higher voltage supplies have failed suggests that there is some incompatibility between this supply and its use for driving tattoo machines!

author: MrZwing
author_rank: Regular Contributor
timestamp: October 05, 2014, 10:37:23 am
content: HelloHmm I will take a look at the schematic of the power supply.I will start a teardown and take pictures, but since I'm a rather beginner i wont know much about the innards of the machine.I'm also started to look on transformers too find witch type gives the most stable output, also reading about switching power supplies want as clean output as I can. but I will probably make a standard LM317 supply for my self and my lab.

author: MrZwing
author_rank: Regular Contributor
timestamp: October 05, 2014, 01:42:34 pm
content: Here is the Teardown of the Cheap ass power supply.hope it's not to long and it has enough details cant say much how it works though new to this.Rating:Input: 100-240V50-60HzOutput: DC 0-18V 2AThe front show membrane puchbuttons and a display for voltage.backside with the inputs and outputs no need for explanation really.the control board was separate from the power converter board.The display was mounted with a couple of screws and shows a 3 digit 7-segment display.at the back I punched in "SJ-DC036" in to google and it showed as suspected a off the shelf cheapo voltmeter readout.though the one I found had only 2-wires this one had 3.Here is how everything was hooked up (minus the display)Cheap basic inputs for the Tattoo machine and foot pedal.1 img: shows the flat cable hooked up to the buttons at the front2 img: obviously shows the backside.3 img: here you can clearly see the L7805CV 5V voltage regulator for the IC's.The other TO-220 with the grinded edge is a F9C24N P-channel transistorhttp://www.datasheet-pdf.com/datasheetdownload.php?id=673248the one marked U3 is a TY34063 DC/DC Converter control and U4 is a LM358 Dual OP-AMP.The plastic wrapped black thing (L2) is an inductor with no printed value.1 img: under the power circuit where you can see a UC3843A SMPS Controller.2 img: under the large cap showed nothing special but a few resistors.3 img: the thing that is stuck to the side of the large cap is a KBP304 Bridge Rectifier Voltage Range 50 to 1000V 3.0A built to be cheap " Reliable low cost construction techniqueresults in inexpensive product". The TO-220 is a P4NK60ZEP N-channel 600V transistor. the small 4-pin ic is marked 817B and seem to be a Voltage Regulator (Positive Output Voltage)High-precision. there is also a small TL431A Programmable Shunt Regulator up to 36V. the small Transformer? has no visible values.

author: MrZwing
author_rank: Regular Contributor
timestamp: October 06, 2014, 06:13:53 am
content: Been studying several circuits of different power supplies and thing I started to understand the basics of it, going to get some schematics of tattoo supplies and compare the similarities witch should be many but see where i can improve on the design's./MrZwing

author: IconicPCB
author_rank: Super Contributor
timestamp: October 06, 2014, 07:33:09 am
content: A bad application of a switch mode power supply in an appliance designed to penetrate the skin.Look at the solder side creep distance ( space between extra low voltage and low voltage ( primary AC side)).Death in a tattoo machine.

author: planet12
author_rank: Regular Contributor
timestamp: October 06, 2014, 10:44:54 am
content: The 817B IC is an optocoupler, used to close the control loop of the regulator over the isolation boundary.... the isolation boundary which is severely compromised by the PCB layout. @IconicPCB is right - this is a death machine. It wouldn't pass any reasonable safety certification, let alone medical grade.The primary-secondary isolation is likely enough... under absolutely perfect conditions. Dirt, dust, humidity - or a spike on the mains - and it'll break down, and someone's gonna have a bad time.

author: MrZwing
author_rank: Regular Contributor
timestamp: October 06, 2014, 12:49:14 pm
content: Well i knew this was a bad quality, didn't know how bad but it's a good "do not build like this" example. haha

author: Rerouter
author_rank: Super Contributor
timestamp: October 06, 2014, 07:36:41 pm
content: more along the lines of improve on this, most of the creepance issues could be fixed with a pcb re-spin, and to acknowledge that for a medical device that penetrates the skin you want to be certain that your not suddenly going to have mains pumping through it,

author: MrZwing
author_rank: Regular Contributor
timestamp: October 07, 2014, 07:45:39 am
content: Well I don't think the one who designed this had quality and safety in mind.I am going to read up on regulations and design my circuit to be beyond safe. maybe put the AC/DC circuit on a separate PCB or something with shielding.I know overkill but that is the way I roll.