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Full details on creating good sound – I haven’t even been able to find a simple VU meter or peak detection circuit which doesn’t use 4 or fewer LEDs. Another thing is I would love to build a high-quality preamp board which I can use on all amplifiers from bass to tweeters 2 channels and stereo, so that would generally be 20 Hz to 20 kHz. I would work with a class AB amplifier also something using FETS which can be easily upgraded in terms of power rating since I would generally go for high powered amplifiers and 2oΩ would be the target for connected speakers 2 channel also. Read more
Switching power supply much lower output than LTSPICE model – I’ve been through several iterations of a specialized switching power supply. It underperforms its LTSPICE model by a factor of about 2, and I don’t understand why. Here’s the schematic: Read more
Sticking a thermocouple junction to a FET case so as to measure its temperature –
We were also wondering about just using Kapton tape to stick the thermocouple end to the fet case….and just squirting some thermal paste over the thermocouple end before the Kapton tape is applied so as to give better thermal coupling of the thermocouple junction to the FET case. What do you recommend for thermocouple attachment to FET cases? Read more
Using audio amp as a power inverter – I made a few simple inverters and also simple amplifiers and I have noticed that audio amplifiers produce a pure sine wave. I realize that audio amplifiers clip when they are overdriven (passing the supply voltage or current). If I am to use an audio amplifier as an inverter the best way I think to get high power would be to use several batteries in series to achieve a higher voltage. But what if I want to use 1 12v battery but be able to pull high current from it? Read more
5 amp power supply troubleshooting – P_tot = I x U = 1.5A x (12.2V – 9.8V) = 3.6W.
For sure it becomes warm …. without a heatsink it’s getting hot, I even assume too hot to survive. What’s the regulator minimum (ripple) input voltage? Read more
Why is the internal resistance of brush DC motor not constant? I am applying different PWM values to a 24 V brush DC motor and taking some measurements of armature current, because I want to calculate armature resistance, however, the armature resistance is changing with applied PWM. Read more
Solution for relay burning issue – We have a product to control 3phase agriculture motor. We have deployed many units in the field and during rainy seasons our product is getting damaged. I have shown device connection diagram in attached image. Damage is happening to Relay and all the semiconductor components on the board. Relay contact tracks on the board is melting out and all the GND and VCC tracks on the board are damaging. Read more
Wanted CC-CV regulated power supply circuit – I want to construct CC-CV regulated power supply circuit for laboratory bench use. The specification is input voltage 34v after filtering from centre tap transformer 12-0-12 @ 5 Ampere, output voltage 0-30V and 0-5ampere, variable. It should work in constant current mode and constant voltage mode. Read more
Offline 150W LED drivers sometimes blow up at Mains Power up Test – 10% of our LED drivers are blowing up on Mains Power ON test. Do you know why? We had very many 230VAC, 150W, offline LED driver PCBs made to which we add (by hand wired modification to PCB) two 100nF X2 capacitors to help them through EMC. Read more
Size of thermal vias for SMPS PCB – Do you agree that thermal vias to go in and around the pads of a D2PAK FET on an FR4 PCB should be no more than 0.35mm in diameter? I am speaking of non-solder-filled vias and PCB with 70um copper thickness. Also, for those thermal vias that are around the D2PAK (ie not underneath it), they should be no closer than 1.7mm to each other (center to center of thermal via). Read more
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