20VAC stepdown to variable AC from 0-12VAC........

[adax811]

20VAC stepdown to variable AC from 0-12VAC........

any suggestion and tips are welcome...




ps: how to use this forum [search engine]?? 500++ pages.....

 

[Willbe]

20VAC stepdown to variable AC from 0-12VAC........

any suggestion and tips are welcome...




ps: how to use this forum [search engine]?? 500++ pages.....

What current you need?

 

[adax811]

Here the willing Volume controller, the % proportional to VAC....

i do this regulator for a 20VAC 50Hz Vibrator.... to regulate the 20VAC.

i dunno the amperes running in the vibrator.

any idea on it?

i'll always here to wait ur answer..... hope u can reply me as soon as possible.. thx

 

[adax811]

I found this on website....... but wat should i modify the circuit to adjustable from 0 to 12 VAC..... im still think about on it..... who which got idea can post a reply............

 

[Hero999]

You could wind your own variac.

Another option would be to just stick a high powered variable resistor in series.

 

[adax811]

wat do u mean a high powered variable resistor in series. can u explain in more detail?

 

[Hero999]

Sometimes it's called a rheostat.

It's just a resistor that you can adjust to alter the current flow, if you know the impedance of the vibrator then you can easilly work out the required resistor value for the required voltage. Start by measuring the current with a multimeter and work out the impedance using Ohm's law.

 

[k7elp60]

20VAC stepdown to variable AC from 0-12VAC........

any suggestion and tips are welcome...




ps: how to use this forum [search engine]?? 500++ pages.....

What are the current requirements for the 0-12VAC

 

[adax811]

wat i need to do to get the current? im newbie...... wat i just know is
when VR 100% - 12VAC, 75% - 3.2VAC, 50% - 2.1VAC, 0% - 1.2V.

i m modifying the circuit that i upload. i exchange the fixed R into a VR

 

[adax811]

for the current i think it'll need high enough for running the vibrator. is it use a Ampere CLam meter to check the A when the vibrator is running?

this is my modification on this circuit.

i add in a 10k ohm VR and replace the R1, R3 into 320 ohm and R2, R4 into 460 ohm.


wat i get is (input voltage is 28VAC, which outpur from my transformer for doing experiment)

when 2, 5 near to 1, 4, (0%), the voltage is 1.18VAC.

50% = 2.00 VAC

75% = 2.23 VAC

100% = 13.63 VAC



(the R1 and R3 will hot when VR set to 100%), who know the reason?

who know the calculation the suitable R1, R2, R3 and, R4 when 10k VR is used and the input voltage is 20VAC.



p.s.: im no so familiar to the LM317..

 

[Hero999]

The LM317 regulator circuit prtoduces a clipped sine wave which might not but acceptable for your application.

 

[adax811]

What are the current requirements for the 0-12VAC

i measure the ampere when i applied 20VAC to the 20VAC 50Hz vibrator, wat i get is 0.7A....

so wat is ur recommend or advice?

 

[adax811]

The LM317 regulator circuit prtoduces a clipped sine wave which might not but acceptable for your application.

ya u r right..... i've made my circuit and tested at the supply to the application. the vibration not acceptable. PLus, the VR fall into same situation as last time...... wat for make this circuit......

if i making the rheostat, how do i make that? and website or tips for me? how i get the part.......?