As shown in the figure, JDQ1~JDQ4 are the direct output control of single-chip IO respectively. The relay, transistor, and power supply in the figure are severely heated. Is this the reason?
Margo Posted on August 17, 2020
After the resistor is connected in series with the relay, its partial voltage is not constant. When the power supply voltage changes or the load changes frequently, the partial voltage also changes, causing the resistor itself to heat or the coil to heat and even affect the normal pull-in of the relay. The diode partial voltage is constant. It is much more stable. Of course, it is also feasible to connect power resistors in series where the requirements are not high.
Yuri Posted on August 17, 2020
Remove the string resistance in the relay circuit.
Lars Posted on August 17, 2020
The big relay is really hot, it doesn't matter, the power supply is hot depends on whether you are switching power supply or linear power supply.
