Simple power supply for Metcal 13.56MHz induction soldering irons  - Page 1
Forum section: electronics / projects

author: lapot2
author_rank: Newbie
timestamp: September 28, 2021, 08:57:40 pm
content: For the administration, and those who have questions.I say right away that I temporarily cannot post a full article here, and I will leave a link to the Russian-language original, and there you need to register, correctly specifying the city, age, gender, and equipment used for electronics repair in the profile (verification is done manually by administrators) . The original article is mine too. The translation here is done via Google Translate, since I don't know English. Over time, it will become possible to post complete and high-quality translated material. If it doesn't match your rules, you can delete it.The diagram is aimed at those who have no experience in the construction of HF transmitters, the idea is that the design is extremely simple, the parts are available, and the minimum configuration steps are taken.I'll tell you right away about the need for a whole bucket of the same type of sting at different temperatures - this is a myth invented by those who did not even hold this equipment in their hands. It is enough to cover all the needs of only three or four stings of different shapes of medium temperature, and one hot one for special cases - such as buckets, pots, basins, sealing holes in a car, and ceramic printed circuit boards.With a 24V supply and a current consumption of no more than 2.2A, the output power is 20-30W, but it can be significantly increased by increasing the supply voltage. With an output power over 50W, it is desirable to use more powerful transistors in the output stage.For the sake of simplification, the design has a low efficiency, but the goal is different.The difference from the already existing factory and home-made samples is that the circuit is simple to disgrace, and at the same time does not require scarce cores, selection of parts, careful coordination of the buildup and the final stage, is not critical to replacing transistors with others with different interelectrode capacitance, does not require searching and ordering rare parts, manufacturing a complex printed circuit board, can be assembled or repaired literally with parts from the trash heap, and at the same time will work immediately. The main thing is not to deviate much from the denominations, and to do everything as close as possible to the description.Due to the use of cascode switching of transistors in the final stage and operation closer to the active region, it was possible to reduce to a minimum the influence of the Miller effect, and thereby achieve stable operation at low power of the final stage, reduce the requirements for the details of the output n-circuit, and avoid the use of a resonant circuit in the gate the circuit of the final stage and the associated problems with tuning and selecting transistors according to the input capacitance, as well as avoiding the use of special high-voltage RF transistors, or simply expensive ones with good frequency parameters.With all this, as well as the use of a P-loop in the load of the output stage, and the use of VSWR feedback for automatic displacement of the operating point Q3, it was possible to achieve stable operation even with the load disconnected, while the output voltage does not exceed dangerous limits for parts, especially quite low-voltage transistors, and a load break protection circuit consisting of RL1, C24, and L8, if you are too lazy, you can not install it, nothing terrible should happen (I did not even install it on the breadboard, and then I added the first simplest thing that came to It works by grounding the DC output with the low active resistance of the tip).Well, of the minuses, we pay for this with serious requirements for the heat dissipation of the output stage transistors, even better with active blowing (both low-voltage sources allow you to connect a fan from a computer, or, as I was prompted by the option, to use a radiator from AM2, or an old powerful video card together with a native fan).Also, when you can raise the efficiency of the device to 98% by installing a frying pan on the top cover of the block, and when working, cook with fried eggs for lunchSetting:Bring RV1 to a minimum, connect a soldering iron, apply power through an ammeter, the current must be 2A or more.After reaching the rated temperature, the current should fall 2 times and jump within small limits.If necessary, rotate the RV1 engine to achieve the minimum possible current, with a confident recall, by a sharp increase in current by a slight decrease in the temperature of the tipAllow the soldering iron to cool down and reapply power to ensure correct operation.When the supply voltage rises, the power also increases significantly, but when it rises above 2V, the operating point must be corrected using RV1.to be continued ...Use only metal housing, connected to the common wire of the circuit and ground !!!To reduce the power of the standby mode, powerful magnets must be placed in the soldering iron stand on both sides of the tip.The magnets, their orientation, and the distance are selected experimentally according to the minimum current consumption on the stand.Constructive criticism and advice within reasonable limits are welcome, as there has been no experience with powerful RF devices,and the theory on them smoked from scratch a couple of months before the creation of this topic.During the development, materials were used:https://patents.google.com/patent/US4626767A/enhttps://docs.google.com/viewer?docex=1&url=http://colinoflynn.com/wp-content/uploads/2012/05/MX-500P-11.pdfhttps://www.eevblog.com/forum/projects/diy-metcal-13-56-mhz-rf-supply/https://www.eevblog.com/forum/projects/i-built-the-diy-metcal-compatible-soldering-station/https://habr.com/ru/post/412607/http://dl2kq.de/soft/6-5.htmhttp://dl2kq.de/pa/1-2.htmhttp://dl2kq.de/ant/3-21.htmhttps://vpayaem.ru/inf_p-contour.htmlhttp://randomfunprojects.co.uk/metcal.htmlhttp://ur8qp.com/publ/5-1-0-48Titov A. A_Transistor Power Amplifiershttps://ru.wikipedia.org/wiki/Classification_Electronic_Amplifiershttps://unexpocom.files.wordpress.com/2013/02/manual_pro5100.pdfhttps://digteh.ru/Sxemoteh/RejRab/E/https://digteh.ru/Sxemoteh/RejRab/C/https://radioaficionsdr.es.tl/Amplificadores-Lineales-RF-.htm1KW Class E 13.56MHz Single Device RF Generatorhttps://www.ixys.com/Documents/AppNotes/CO1.pdfhttp://zpostbox.ru/radiopriemnye_ustroistva_na_polevykh_tranzistorakh.htmlto be continued ...The article will be edited and supplemented with materials of varying importance as far as possible. Be sure to reread!Subscribe comments about your experience in assembling and setting up, you need to learn the repeatability of the design in practice!Copying of materials is prohibited without the consent of the author and reference to the source!Original articlehttps://youtu.be/-SXZdOlCfWU

author: thm_w
author_rank: Super Contributor
timestamp: September 30, 2021, 10:36:58 pm
content: QuoteWhat about running the supply at 48V? Where would the limitation be.QuoteEven the official product has a low efficiency, 45-55% depending on the model. Did you measure its efficiency?

author: lapot2
author_rank: Newbie
timestamp: October 01, 2021, 07:25:43 am
content: I did not measure normally, there is nothing yet ... at a load of 50 ohms to 120vpp.but I think there is a high SWR, I will assemble the SWR meter - I will measure it.48V will be a lot, 32V is enough to get 200vpp at the output, while the current consumption is closer to 4A, and I did not supply any moreI have not seen the real ones, and I hardly will see them, and even more so I will analyze them for experiments (it costs too much in our area (

author: lapot2
author_rank: Newbie
timestamp: October 05, 2021, 08:45:35 pm
content: SWR at idle with a hot tip 1.2 (VPP 36V), when soldering 2.2-3 (VPP 80-120V). Sting STTC126, power supply at the same time 22-24V, current from 0.6 to 2.6A