Circuits FAQ

This is the Archive of Electronics Design related Question & Answers. Ask Questions at EE BBS FAQ. To get a project designed by delabs visit Design Service.

Search This Blog

Thursday, September 17, 2020

A Button and four LED Lights

Need a design - Simple one button push button to turn on 4 different LED (3mm Dome) every time you press the button. 


Attached is a circuit file that might work for you. Or make it simpler combining it with the circuit shown below.  555 Oscillator and Running Lights

A Button and four LED Lights

Make a monostable with 555 as shown here - 555 Timer based Circuits  -  and output it to a 4017 with above info, i am sure you can build or design what you want.


Temperature control for CPU

My name is IS and I am looking for somebody to design and build a simple circuit that controls a small computer fan using either a 120V plugin or a battery using a temperature switch...

In other words I would give you the set point and at that temperature it would turn on the fan and when it drops below the set point it turns off the fan.. the temperature would have to be measured using a contact type measuring device like a thermocouple or thermistor.

Mail from IS Brazil

See Craig's thermostat circuits

Try this One Chip solution from Maxim Semiconductor - MAX6641 temperature sensor and fan controller -

MAX6641 temperature sensor and fan controller

"Accurately measures the temperature of its own die and the temperature of a remote pn junction. The device reports temperature values in digital form using a 2-wire serial interface. The remote pn junction is typically the emitter-base junction of a common-collector pnp on a CPU, FPGA, or ASIC."

Some of my circuits are here Industrial Process Control Circuits


Wednesday, September 09, 2020

Motor driver H-Bridge partial

I envision a design based on the ST TD340 (page 19 of attached spec.) utilizing the power MOSFET IRF3709S (attached spec.) with external PWM-Signal (provided), separate external controller supply 20-30VDC (provided) power supply for H-Bridge up 20VDC 50A (provided) with screw-terminal type connections for control and power enclosed in a (preferably) DIN-Rail mountable enclosure that would be housed in a control cabinet (dry, 30-40C)


This part below means that you have a 20V-50A DC supply which will power this system ?

Motor driver  H-Bridge partial

"50 amp power supply with 6-18v regulator in a Board size 72mmX120mm"  separate external controller supply 20-30VDC power supply for H-Bridge up 20VDC 50A