Recent content by mdjensen22

If you need more current gain, try using a darlington pair (assuming BJTs) http://en.wikipedia.org/wiki/Darlington_transistor

The motor speed given is making assumptions that a 2 pole motor is being used. http://en.wikipedia.org/wiki/Induction_motor#Synchronous_speed If using a universal motor or brushed DC motor (common in vacuum cleaners and other appliances), the speed is going to be all over the place...

What output power are you looking to get?

Some of it depends on if you're using PTH or not. I was always told to give an extra 5mils for plating on top of a standard 10 mils over the max diameter of the lead per the data sheet. It has served me well. To answer your question, I'd use 65 mils as the basis and then round up to the...

OP - Something to think about: circuit breakers are specifically designed to have a 'time lag' so that they open on fault conditions but yet don't trip every time the washing machine, refrigerator, lights, etc. turn on. Anything with an inductive load (incandescent bulbs, motors, etc) will...

You probably don't want to switch relays as fast as your application will want. In addition the power supply requirements are much higher for driving relays as opposed to driving transistors. Go with the transistors.

why would you suspect a higher current draw from a counter EMF? Counter EMF is what causes the motor current to drop from the inrush levels once the motor starts spinning. Counter EMF is inherent to a motor, so I think you'd be hard-pressed to argue that it has some adverse effect on the...

My bad - I just went by their little check box that said "isolated". I guess I could have looked at the doc. On Semi has one they are marketing as isolated as well. This may be worth looking at as well... http://www.digikey.com/product-detail/en/NCP1606BOOSTGEVB/NCP1606BOOSTGEVBOS-ND/2337352

Typical kitchen appliances use universal and DC motors. They are inexpensive, easily controlled, bidirectional, and relatively lightweight. Based on your speed request, you might want to get a gear motor, or you'll have to make your own gearing system since motors typically run much higher...

Does something like this http://www.powerint.com/sites/default/files/PDFFiles/rdr236.pdf work? (380V). It's overkill in terms of current, but it can be purchased which saves you some trouble if you only need a one-off. http://www.digikey.com/product-detail/en/RDK-236/596-1418-ND/2533771

telecom or reed relays might work for you. With telecom relays you can typically get latching coils too which is nice because you don't have to constantly energize the relays (keeps your power requirements low if you decide to connect/disconnect all simultaneously). Are you planning on...

Jim, that was awesome as always.

How important programming is depends on what area of EE he goes into. This question comes up a lot and there are those that will speak down on its importance; there are those that will regard programming is critical. From what I've seen, we almost all do some level of programming whether...

I have a motor that is running off bridge-rectified mains voltage. There are no filtering capacitors across the rectifier output. When figuring the ratings needed for any switches in series with the motor, would I use the AC or DC ratings of the switch? My understanding is the biggest...

Consult the datasheet of your device for specifications, but as was stated above, it isn't good practice to count on the internal protection parts for much of anything. Most of the internal protection diodes are relatively slow and cannot handle a lot of power. A simple RC LPF can do wonders...