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  1. Hi, Anyone know how to create/design for the PCB spark gap? I found limited information on how to create the spark gap on PCB. Any requirement needed to follow? For your information, spark gap can provide significant protection against voltage transient. Regards
  2. Actually the R3 shd be the load and a max of 1A must be able to supply to the load from another current driver circuit. A protection circuit to turn off the switching circuit is needed when user accidentally short the output (load removed and short to ground).
  3. thanks audioguru for the suggested solution. ;D
  4. Let say if i have a transistor switching circuit as in the diagram (attached image), by switch on the J1, the voltage drop across Q3 will cause damage to the transistor. Is there any way to add a control circuit to turn off the Q2 so that Q3 will off as well. Thank for the opinion as i start learning designing electronics circuit now.
  5. Is that possible to design single supply op amp (O-5V) rail-to-rail, to provide a negative ouput voltage?
  6. yes...the measurement was done without load..with load it definately higher(with 25ohms at full load). the desired max output is 25V 1A. the 32VDC is supply to power transistor circuitry to output the desired voltage.
  7. hi..i noticed that my power source (24-0-24 rating transformer connected to full wave bridge rectifier and filter out by 2x4700uF, 1000uF, 0.1uF and 5.6K resistor all in parallel) having a ripple noise of around 4mV-8mV. Any idea to further reduce the ripple noise? and hopfully can reduce my overall PSU ripple. Any formula to calculate the ideal cap value? thks and regards.
  8. Okay i'll try to troubleshoot further and will notify if got any improvement over the ripple noise...thanks for the guidances.. :)
  9. to ante sorry if i posted the thread in a wrong section :P well actually the 6V 5A is just a single power supply output, in facts, my PSU consists of +25V 1A and -25V 1A of output as well. Since now in the troubleshooting stage, i dun intend to mess up all the part as it complicated the situation. Further, the +25V/-25V supply is separated with the 6V supply. After the transformer is the bridge rectifier, so there isn't any regulator for the AC to DC voltage. the only regulator circuit i have is the LM7815 and LM7915 for the op amp. the output is control by 2 power transistor based on the control signal from the MCU. to audioguru, i cant get the freq of the signal from the scope as the scope indicating several MHz. Is that possible? I think something wrong with the reading or scope setup. Even the ripple noise rms of the scope is different from the meter reading. the op amp i used is LF412 from NS or TI.
  10. thanks for the reply at 1st... well...my PSU actually nothing but juz consists of a transformer, brigde rectifier and +15/-15 voltage regulator for the op amp. so i guess there isn't any switching regulator in my PSU. as wat i stated early...the ripple noise can be reduced to <2mV by applying filter capacitor at the 2 output terminal of the PSU. the problem is i not sure the exact value of the capacitor and type to further reduces the ripple. another problem of applying filter cap at output caused voltage to drop during full load. I cant figure out wat causing the voltage drop. Furthermore, i dunno shd i use the LC filter, RC filter or etc methods. thanks and regards
  11. I have a question here...i currently doing a power supply which is capable to supply max of 6V and 5A of output. the PSU is a digital PSU with microcontroller and LCD interface which means that the output can be adjusted to any desired value. the problem is the output ripple noise of the PSU is not really satisfying. Maybe can apply some filter circuit on the output terminal of the PSU. Am i rite? But my question is how to choose the right capacitor type and value? I try with a 470uf electrolytic capacitor but the problem is it causing slower stepping down the output voltage, let's say from 6V to 1V (in fact it shd be instantaneous). Any solution to that? All helps and advices are highly appreciated..thanks 1st.
  12. i would like to hav a copy as well...thx so much dennistcl@gmail.com
  13. hi guys..i need some help on this protel software.. i got the schematic and go through all the procedures until i get the PCB layout. but i dunno how to print out this layout so that i can transfer the circuit to PCB. if i select print option..it will print out the layout fixed to whole A4 size paper..which is not the exact size to the real component.. can somebody help me? really appreciate it...
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