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  4. That sounds like a major project. One would want to use a microcomputer as it would simplify the circuitry greatly. Example: https://www.youtube.com/watch?v=9IWWa0xCd04&feature=emb_logo It is said that power supplies are less expensive today for EDM machines, perhaps you could search on the internet for a good price. I would thing that 2950 pounds is expensive: https://baxedm.com/product/bx17-arc-generator/ I have an eight inch steel disk that I want to make a 100 tooth socket from - an electrical discharge machining would be great for that I would think.
  5. I would think that is a good solution. A more elegant solution would be to use a temperature control switch in series with the fan. They are not very expensive. You want one for example: less than 25 degrees normally open and higher than 25 degrees normally closed. Only a computer could generate a url that bad! https://www.ebay.com/itm/Temperature-Switch-Control-Sensor-Thermal-Thermostat-25-C-77-F-N-O-KSD301-q-e/333383230245
  6. I am a greyhound trainer. I have a pillar/capstan dog walker connected to to 240v AC power supply I'd like to be able to vary the speed of the dog walker and also have a dead man's switch Any ideas?
  7. I am a greyhound trainer. I use a starting motor with car battery rig to drive a lure for the dogs to chase. its operated by a simple on/off switch I'd like to vary the speed - any ideas
  8. I found this description of our PSU by Rod Elliott on www.sound-au.com and he also introduces some improvements and shows how to use this power supply as bipolar unit. The schematic below is an example, and although simulated it's not been tested on the bench. Copying description: A single supply might be attractive for some people, and it's certainly simpler than a dual tracking version. Of course, if you only have one polarity that limits your options as to what you can test, but they are commonly available from any number of suppliers. The circuit shown below is adapted from one that's shown on a number of different websites [2, 3, 4]. As such, it's difficult to know which one was 'first', and there have been many improvements (or at least changes, which aren't always the same thing!) made to it over the years. The basics haven't changed much, and the one shown below dispenses with one voltage regulator in favour of a simple diode regulated negative supply. Because I used LM358 opamps, the negative supply only needs to be around -1.2V at fairly low current. When the supply is in current limit mode, the LED will come on, indicating 'constant current' operation. It's normally off, so you can tell at a glance if the load is drawing the preset current with a reduced output voltage. Constant current operation is particularly useful for testing high power LEDs or LED arrays, as that's the way they are meant to be driven. You also need an 'on/ off' switch, which reduces the output voltage to zero when in the 'off' position. This is an essential feature (IMO) as it lets you make changes without having to disconnect the supply. The best arrangement is to provide the switching at the output of the supply, as that lets you set the voltage while the DC is turned off. Consider using a relay (or two) for the switching, otherwise you need a heavy duty switch. Wile the voltage can be reduced to (near) zero by pulling the non-inverting input of U1B to ground, there may be 'disturbances' when AC power is first applied. This is avoided by switching the output. The supply shown below is fairly basic, and you'd need to add meters for voltage and current, and thermal management (a fan and over-temperature cutoff) at the very least. There are countless improvements that can be made, but they would make the circuit more complex, more expensive, and provide more 'exciting' ways to make a seemingly minor error and cause the supply to blow up the first time it's switched on. U1 is a 7815 regulator, but with a 15V zener from the 'ground' pin to raise the voltage to 30V. Additional zener current is provided by R3 to ensure a stable output. U2A is the current regulator. When the voltage at the inverting input (U2A, Pin 2) is greater than that on the non-inverting input (Pin 3), the output goes low, pulling down the reference voltage provided to U2B (the voltage regulator). The voltage is reduced by just the amount required to ensure that the preset current is provided to the load. The current limit is variable from (theoretically) zero to 2.5A. VR4 allows adjustment to ensure the reference voltage for U2A (TP2) is as close as possible to 825mV (825mV across R18 (0.33Ω) is 2.5A output current). It may be possible to increase the output current to 3A (990mV reference voltage), but you would need to add another series pass transistor to keep the transistors within their SOA at minimum voltage and maximum current. Some ripple breakthrough at maximum output (voltage and current) is likely unless you add more capacitance (C1). When in voltage mode, U2B compares the reference voltage from VR2 with the voltage at the output, reduced by R16, R11 and VR3 (voltage preset). If the output falls due to loading, U2B increases the drive to the output series-pass combination (Q3, Q4 and Q5) to maintain the desired voltage. The upper output voltage limit is imposed by the opamp (U2), which can't force its output to much above 25V with the typical output current of around 2mA (this depends on the gain of the output section, Q3, Q4 & Q5). Note that the reference voltage is itself referred to the negative output terminal - this ensures that the regulator will correct for any voltage drop across R18. If it were otherwise, regulation would be badly affected, especially at maximum current. Note that the heavy tracks are critical, and any significant resistance in these sections will upset the current sensing. Also, be aware that the points indicated with a 'ground' symbol are marked 'Com' (Common). They are not connected to chassis or any other ground. The 'Com' designation means only that all points so marked are joined together. Also note the diodes with an asterisk (*), which must be 1N5404 (3A continuous) or better. All other diodes are 1N4004 or equivalent (other than the 25A bridge rectifier of course). Bench power supplies often get connected to 'hostile' loads, and the high current diodes (D8 and D9) are to protect the supply. The supply uses 'low side' current sensing, so it needs some tricks to use it as a dual tracking supply with both positive and negative outputs. The current sense resistor (R18) is a compromise between voltage drop and dissipation. At maximum current (2.5A), R18 will dissipate a little over 2 watts, which is easily manageable using a 5W wirewound resistor. Both voltage and current regulation are very good (at least according to the simulator), and there's no sign of instability. In theory (always a wonderful thing), the current can be regulated down to a couple of milliamps, but in reality it will not get that low. Expect around 50mA or so, but it might be a bit lower than that (depending on the opamp's own DC offset). Another trimpot can be added to correct for opamp DC offset, but it shouldn't be necessary (and adds something else that needs adjustment). All of the alternative versions specify a single 2N3055 for the output, but with a shorted output and maximum current, the dissipation will be about 80W, and maintaining the series pass transistor(s) at 25°C will be impossible. The TIP35 devices have a higher power rating (125W) and a good SOA (safe operating area), but there is still a case to be made for using three, rather than the two shown. The BD139 also needs a heatsink, but a simple 'flag' type will normally suffice. In common with any transistor that dissipates significant power, excellent thermal bonding to the heatsink is essential, and you will need to use a fan. This can be thermostatically controlled, and can use PWM (pulse width modulation) for speed control, or it can just turn on and off. Figure 8.1 shows a suitable circuit for both operating the fan and shutting down the supply if it gets too hot (which in this context is no more than 50°C heatsink temperature). The original article has many more information and useful add-ons. Read more here: https://sound-au.com/articles/bench-supply.htm
  9. Hi everyone my new subwoofer with cooling fan dependent on temperature which does not run upon power up. Several hours of continuous operation listening music at home with lower volume wherein the fan is still not running but I can sense 45degC on its metal casing. I wish to revised the fan circuit to permanently running upon power up for optimum protection of amplifier circuit. I wish to have your comments if what I will doing is correct.
  10. Hi I am looking for a bit of direction with a project . Some time ago I bought a Spark Eroder or EDM (Electrical Discharge Machine) Mechanically it is very sound, but the power supply is I think beyond economic repair. As I understand the power supply it works between 0 volts and 100 volts Square Wave with a variable output current from 10 to 50 Amps. Also both the off time and the on time are separately adjustable. I believe the original system used a lot of power transistors which were switched by push buttons to obtain the correct power setting. I am sure someone out there with a better understanding of modern electronics will have a good idea of how to achieve the supply I need to build. Thank for looking, any pointers would be very much appreciated. Jonathan Smythe
  11. You can download the data sheet from here but it contains little useful information and the diagram is not the correct one. http://www.bldcmotor-driver.com/sale-11494096-500w-brushless-dc-motor-driver-hall-effect-24-volt-dc-motor-speed-controller.html the link is near the bottom of the page. One could buy a board?
  12. Do you think that it is enough to know the size of the board due to the slight distortion (width and length) and what about the accuracy? Sincerely yours, Daniel
  13. By pads do you mean the pads (marked hall) on the lower right of the board? If so knowing any dimension on the board, like a component, one can find other dimensions using a tool like photoshop or the poor man's version THE GIMP. Also knowing the board is 63x42.5x17 mm (L*W*H) one could scale it off the screen. this thing will not go away delete yourself ! Also there is a manual in English here but the link is broken - you may request one perhaps. http://www.brushless-dcmotor.com/sale-11954921-jyqd-v7-3e3-3-phase-brushless-dc-motor-driver-15a-current-pwm-speed-control.html
  14. Oh sorry, of course I meant the JYQD V7.3e3 and not the 7V that doesn't exist. But I still only find the old version. I would need the dimensions of the pads or the distance from them to the edge to create the circuit board. Do you have any suggestions? Kind regards, Daniel
  15. Searching for: JYQD-V7.3E3 on Yahoo will give you a few hits. Not _7V good luck
  16. Has someone the new datasheet from the JYQD_V7.3E3 motordriver (24V) (that one with the hall sensor pads on the side and not the regular one that it is aligned) DC-12-V-36-V-15A-500W-Senza-Spazzola-Del-Motore-Sala-BLDC-Bordo-di-Driver.jpg_640x640q70.jpg_.webp
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  18. hi guys, i have the original kit from greece , i made it in 1995 and some day it was burned. i did the audioguru rev7 update with mc34072 and all the changes. only thing i didnt change is the 12000 cap , i am using 2x3300/63v cap and 28vac transformer. VDC is 39volts , ref voltage is 11,8 , negative voltage ok . i have checked all components twice.then the following happened: when i increase the voltage , it goes from 0.0 to 30.0 SHARP, BUT at 6.7 volts there is a "jump" from my panel ANALOG voltmeter to 8,7 volts ! i checked with the oscilloscope and it appears that at 6,7 volts there is a huge noise that the analog voltmeter averages and thats the cause of the "jump". if i use a load that requires less than 6,7 volts everything works fine , lets say 100 ohm load the psu works fine cause it uses less amps (30/100=300ma) and current regulation works fine. if i switch to 10 ohms load (30/10=3A ) that can use the full spectrum of volts and amps ,the power supply goes INSANE , it RINGS SO LOUD , and it even BURNED the C7 cap alive with flames... if i use a 2ohm load , the psu increases the voltage BUT after the 2.2 amp it rings again (till 2.2 amps current regulation works fine). if i short the outputs the psu goes over 3amps no matter what i do with the volts or amps (exception if i use 30volts and i short the output , the current regulation works , under 30volts if i short the output the needle goes over 3 amps the the ringing happens (the needle bounces a lot too). probing at U2 shows insane ringing above 3-4 volts but after 20v it smoothens somehow.R12,C6,C9,C5,C7 seems ok but still lots of ringing.. most ringing is at pin6 of U2 and at the base of BD139. i have checked everything after the blow of C7 in order to see what might be wrong or burned and i really cant find anything misplaced,wrong value,cold joint etc. does this behaviour ring to any of you any bells for the cause of the problem? i am going nuts with this psu...
  19. The LMD18200 is rated 3 amperes and 12 to 55 volts: https://www.electronics-lab.com/project/lmd18200-h-bridge-module-for-dc-motor/
  20. https://www.electronics-lab.com/wp-content/uploads/2015/11/DC_SERVO_MOTOR.pdf Hi, I found this motor driver in the list of projects and its exactly what I'm looking for. However I need 2 amps output to the motor, and this controller is rated at 800ma. So I would be very interested in knowing if there is a way of beefing up the current layout or maybe adding a motor shield? My knowledge is basic but doing my best to get up to speed Also on the original post it sites a place to purchase this as a kit but I was never able to locate such a site? Thank-you .
  21. The IPS6021 is readily available from China via Ebay. There is a supplier in the UK also: https://www.ebay.com/itm/IPS6021RPBF-Intelligent-Power-Switch-High-Side-Active-High-1Output-5-5V-TO-252-5/152755283380?hash=item2390eca5b4:g:U~MAAOSwqXxdNtVK
  22. I'm trying to use an ESP32 microcontroller to control a 12V diesel heater on a narrowboat. I need a high side switch driven by the ESP32 to turn it on and off. On previous similar projects I've used an IPS6021, that was easy to use, just connect the output of the microcontroller to the input of the switch via a resistor, when the output goes high the switch comes on and vice versa. However I can longer find the IPS6021 for sale (discontinued by RS components) so I instead used a BTS50085 (Datasheet) as it's high side switching, sounded similar and I could get it in a TO-220 type package. However this is turned on and off by connecting and disconnecting the input to ground. I assumed this would just mean it would work backwards from the ESP32 point of view, zero volts would be like connecting the input to ground, 3.3V volts would be like not connecting to ground, however the damn thing is on all the time, when the ESP32 is at 3.3V it's still acting like it's connected to ground. Physically disconnecting the input turns it off but nothing else will. I'm assuming there must be a way to get a 0-3.3V logic signal to switch this thing, but how? Can anyone suggest a way I can control this from the ESP32? Or failing that can anyone suggest an alternative power switch that works like the IPS6021 but that is still available in the UK?
  23. Can you add a heat sink to the transistor - is there enough room for it? A 30 ampere transistor needs a good heat sink bolted to it.. Also you need heat sink compound/paste/grease to get good thermal bonding.
  24. There is an old rule that you need at least 2 times the frequency that you wish to view. There is a publication by the ARRL "Oscilloscopes for Radio Amateurs". On Amazon.com is near 20$ used or about 10$ for the kindle version that maybe helpful. The kindle version can be viewed via their free PC app. Also there are videos on YouTube on choosing an oscilloscopes. I have a Hantek DSO5202P it was far more functionality then I need. I did have to replace the display after about three years but they are not expensive. The problem I have is that I answer so many questions that I like to give others a chance to answer some. But that is not always helpful I know. 🤨
  25. 40 views and no advice? 😭
  26. Hi everyone I have a new subwoofer but suddenly it turned off while playing. It's a 1600w and the volume is around 30% while playing. It was a second day of sound test that blown it's fuse when I looked into the power supply board. I found out mosfet 4pcs 40N60M2 shorted. As I analyze on the position of the mosfet it is not bolted into the metal frame but rather fixed on the PCB board and if I remove the board the mosfet is disengaged on the metal frame. In my analysis the mosfet may lose physical contact with the aluminum heatsink that's why it overheated and shorted the junction within the mosfet. I ordered online on the parts but I am not totally sure if the same incident will no longer occur. I will be very glad for your comments.
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