I have just completed a SMPS power supply provided by NUUK at decibel dungeon. I added a three way swithc at the +ve pole a described on DIY paradises's website. When i measure the voltage at postion 1 (270ohm 1/2w resitor) and at postion 2 (no resitor) the voltage is exactly the same. Why is this? I thought that adding the resitor was supposed to provide for a trickle current but i am getting a full blown 12.4 volts?
correction it is a 240 ohm 1/2w resitor. Should i try a higher resitance or is it simple an issue of having not connected the amp yet?
Neil.
The resistor should be connected between pin positions 2 & 3 of the switch.
If this is right then you should get a reduced voltage in position 2.
It sounds as though you are taking measurements with your meter before the resistor. Your meter probe should be placed after the resistor ie. on pin 3, even when the switch is in position 2.
Sorry if I have misinterpreted your problem.
The resistor should be connected between pin positions 2 & 3 of the switch.
If this is right then you should get a reduced voltage in position 2.
It sounds as though you are taking measurements with your meter before the resistor. Your meter probe should be placed after the resistor ie. on pin 3, even when the switch is in position 2.
Sorry if I have misinterpreted your problem.
Need some help, I can't source a 3-step off-on-on switch here, can I use 2pcs off-on switch then put them in series, with the resistor on the "on" position of switch one, while the other end is connected to the "off position" of the 2nd switch? Thus, to prevent the pop, with both switches in their "off" position, I turn on switch 1, followed by switch2. Will this work? Thanks.
Trebla,
This makes little or no sense to me. I have the resisotr placed between switches 2 and 3. I tested this by severing the resitor connection and measuring the voltage and it drops to zero.
I then tried placing the 240 ohm 1/2 watt resistor as well as a 200 ohm 1 watt resistor (i had it lying around) and still the meter reads 12.4 volts. I then added a led in series with the 240 ohm and the volatge trop to 10.4 volts. So i am adding resistance in the right region but the 240 ohm resistor on its own lets 12 volts through. Is there a different resistor i should be trying. Right now i am using a 240 ohm metal film resistor.
What should my volt meter be reading with this resistor?
This makes little or no sense to me. I have the resisotr placed between switches 2 and 3. I tested this by severing the resitor connection and measuring the voltage and it drops to zero.
I then tried placing the 240 ohm 1/2 watt resistor as well as a 200 ohm 1 watt resistor (i had it lying around) and still the meter reads 12.4 volts. I then added a led in series with the 240 ohm and the volatge trop to 10.4 volts. So i am adding resistance in the right region but the 240 ohm resistor on its own lets 12 volts through. Is there a different resistor i should be trying. Right now i am using a 240 ohm metal film resistor.
What should my volt meter be reading with this resistor?
Hi Neil,
If your measurements are taken off from the soldering terminal of the switch, the readings you've seen are correct. All 3 positions will measure the same voltage as the PSU/SMPS.
In order to see the 'soft-start' voltage, the measurements will need to be taken from the soldering terminal at position 3 only (with respect to the negative terminal of the PSU/SMPS); and a load is connected (i.e. - Charlize). When the switch is at :-
1.) Position 1 - No voltage should register on terminal pin 3
2.) Position 2 - About 4V to 6V will be registered on terminal pin 3 (Charlize is connected)
3.) Position 3 - The same voltage from the PSU/SMPS
Hope my explanation helps.
Cheers.
If your measurements are taken off from the soldering terminal of the switch, the readings you've seen are correct. All 3 positions will measure the same voltage as the PSU/SMPS.
In order to see the 'soft-start' voltage, the measurements will need to be taken from the soldering terminal at position 3 only (with respect to the negative terminal of the PSU/SMPS); and a load is connected (i.e. - Charlize). When the switch is at :-
1.) Position 1 - No voltage should register on terminal pin 3
2.) Position 2 - About 4V to 6V will be registered on terminal pin 3 (Charlize is connected)
3.) Position 3 - The same voltage from the PSU/SMPS
Hope my explanation helps.
Cheers.
- Status
- Not open for further replies.