I have a raised floor area with a few server racks on top, the under floor area is used to distribute HVAC to the racks. I have already run all the cables before learning of NFPA75's plenum rating requirement. I'm really struggling to find any plenum rated conduit/raceway with a larger than 2 inch inner diameter. My main question is... is EMT considered plenum rated? I think it is, but more specifically, can I run general purpose wiring through an EMT in a plenum and still meet standards? If I can't do this, any suggestions on sources for plenum raceway/conduit with 3, 4, and 5" inner diameter ..read more

I have designed high frequency full bridge inverter 20 khz. I am using TLP250 as my gate driver and 10n60 MOSFETS. the problem is that it works fine at frequencies up to 2 Khz at high frequency the duty cycle varies the width of the wave but it is not able to switch off fast enough so it is always on as shown in the picture. My doubt is that it need any kind of filter but I do not know how to put it ..read more

Software engineer dabbling in electronics here. With feedback from the previous iterations, I think I have something I can put on a breadboard without putting silicon particulate matter into the air. Would you agree? Q1 and Q2 are P-channel power MOSFETs that get switched by Q5 and Q6. Those are N-channel logic MOSFETs sensitive enough to be switched by 3.3V raspberry pi pins O1 and O2. Q3 and Q4 are N-channel power MOSFETs that get switched by Q1 and Q2, while Schottky flyback diodes D1-D4 take care of reverse current without bothering Q3 and Q4 gates or Q1-Q4 internal diodes. R1 and R2 are ..read more

I am being asked to design a Moore machine which takes in a binary stream as an input and gives out 1 only when it detects the sequence 01011. The solution defines 3 states and proceeds to construct a state diagram. I am fine with the state diagram but where did we get to 3 states? How do I figure that out in a general question? I am only beginning with FSMs ..read more

I designed this boost converter to drive vacuum florescent displays, nixie tubes, and similar devices. It can drive a 10k Ohm load at 235V. I'm sure I can get away with larger loads as alot of the tubes/displays only need a few mA. I am curious as to how others would have designed something with similar functionality, as I'm certain there is a more elegant way to implement something like this. Additionally, any advice on how to improve this circuit would be greatly appreciated ..read more

I am trying to split the GND and power inside the 2nd and 3rd layers, however, there is some dead copper that I can not delete, could you pls tell me how? this picture below is a part of Plain I want to delete ..read more

For an efficient schematic design review, what are the steps to take? Of course this comes with many years experience. But I would like to know what to watch out for etc., e.g resistor values,voltages, current, read datasheet? The entire A to Z of it basically ..read more

What is the amperage needed to activate a 12-volt automotive relay's primary circuit? Is there a safe range ..read more

I'm upgrading the battery on my electric boat. Currently I have a 72v 100ah LifePO4 battery. I have a solenoid between the controller and the battery. That solenoid is attached to the ignition key. I just bought 2 more batteries and I intend to put them in parallel. I'm going to install a solenoid on each one, and then join them on a bus bar, which will then go to the main line to the main solenoid, which goes to the controller. 72v solenoid The goal will be to have a switch on the dashboard for each battery. I want to put an indicator light next to each switch to show the contactor is closed ..read more

I have a petrol mower with an electric-start engine. The electric start is powered by a small battery of similar size and design as you might find on an electric drill or other power tool. After a few years of faithful service, the battery has done what I always knew was going to happen and will no longer hold a charge. Unfortunately, it is no longer possible to buy a replacement battery. It occurs to me that a might be able to jerry-rig an arrangement that allows it to start by using one of the many drill batteries that I already own. The problem is that the drill batteries are 18v - and the ..read more