(editor’s note: Intrigued by the problem? Have a question or optional solution? Then click the “Read more” link and follow the conversation on EDAboard.com or log in to EDAboard and participate in the forum thread.)

Query about crossovers – I bought 2 assembled boards on eBay built around the IRs2092. It’s for 2 mono amplifiers. It says 700 watts @ 4Ω – not sure if that’s peak or RMS. Normally in crossovers, I see big coils,big resistors and capacitors but they are never labeled. I would think those types are passive crossovers. Based on my readings,  active crossover would be the better choice. It is so simple I am wondering if by some chance it will limit the power. Read more

Flux walking detection – What could be a simple method to detect flux imbalance (DC build-up)? I need to measure it for a low-frequency transformer connected to a MOSFET full-bridge (driven by an unipolar SPWM signal). It’s a high power sine wave inverter and I’ve noticed a strabehavioriour (even with light resistive load). Read more

Thoughts on these audio amp circuits – I build amplifiers as my hobby but t that I can never build good amplifiers. I am trying out a new circuit and I want to know how does this circuit look to you guys? The plan would be to use it to increase the volume then use a tone control circuit otherwise to control bass, mid, and tweeter. Read more

I want to add it to this circuit

Transformer’s core size -We know that the mains voltage is 110 sen (2 Π 60 t)

And by the faraday’s law:

is proportional to current. where L is the magnetic path.

And as the magnetic field in the core is constants:

The only staff which can changes is the current, so:

So, in the transformer there is:

And here is my question, the core is made of silicon steel which ≈ 14000 and the saturation magnetici field is 2 [T].

So B can not be bigger than 2[T]

And ≦ 2[T]

I that way A must be and that’s bigger that the commercial transformer. Why? Read more

Puresine wave inverter – I plan to build this inverter but I am seeing some comments about it having a high standby current draw like 6A to 8A. Just, by looking at the circuit do you think this is true and, if so, how could that be fixed. Read more

Troubleshooting 450W amplifier – I build this amplifier circuit last night and I didn’t add all the transistors. I only added a pair for testing. I used 2SC3856 and 2sa1216 for T1,T2 and T3 and I used a BC547. I supplied the board with 40v +/- and I heard a sound out of the amp when I connected it. Across the collector and emitter I was getting about 38v and I was wondering if that’s the problem since that voltage is close to the limit. I used 1n4007 instead and I used a power supply with regulators for testing purposes only. I’m not sure where my problem is. I don’t remember where I got this schematic but it supposed to be functional and tested. Read more

Voltage-mode control using UC3842 – I wonder if I could use the UC3842 PWM controller in voltage-mode control in a two-switch flyback topology. Below is the block diagram. If I tie the VFB pin to ground, I’ll get a constant threshold of 1V at the current sense comparator noninverting input. This way, by applying the output feedback voltage to current sense pin, I could (theoretically) control the PWM duty cycle. The output feedback voltage should be designed using a voltage divider, to get an output of around 1V for the required output voltage. Is it going to work this way? I have some concerns regarding loop compensation, as the output voltage (feedback) is read during transistor ON time, when the flyback diode is not conducting thus the output capacitor is discharged by the load. Read more

Power MOSFET driver for parallel power sources – I am designing an inverter to convert +24 -24v to AC. My microcontroller is working with 3.3V. I don’t know any proper FET driver whose low voltage side works with 0 to 3.3 V and its high voltage side works with -24 to +24V. Can you help? Read more

Switch mode inverter vs. linear inverter – There are two basic types of inverters in the market. One is linear with heavy weight and low-frequency transformer, and the other one is a switch-mode, high-frequency, light-weight inverter. What is the better choice w respect of cost, efficiency, durability, and overall satisfaction? Read more

Transformer DC offset – I’m looking at a design from TI. I noticed that they have used a cap and resistor on the transformer primary side to eradicate any DC offset seen by the transformer. My question is, if the resistor is rated to 1/4W with the currents seen on the primary, how can you have the resistor rated so low in power? Also what;s the best way for calculating the optimum values for this? Read more