However, it is possible to phase a transformer with a voltmeter alone. I use a Variac to apply a low voltage, but a series resistance can be used to limit the current in case of an unexpected short. Apply a voltage to one of the windings, here winding 1-2. We can arbitrarily assign a phase mark to one end of this winding, say terminal 1. Connect the other end of this winding to one end of the other winding. There are only two possibilities, that we have connected to the marked or the unmarked terminal, as shown. Now measure the voltage between terminal 1 and the free terminal of the other winding (this cannot result in a short circuit because of the high resistance of the voltmeter). If you find twice the applied voltage, then conditions are as at the left. If you find zero volts, then conditions are as at the right. Now the second winding can be marked, and the proper connections determined.
To phase the secondaries, measurements can be made in exactly the same way. One winding is marked arbitrarily, the other connected to its other end, and the voltage measured to the open terminal. The secondaries can be phased relative to the primary just as if they were more primary windings, provided low voltages are used and the turns ratio taken into consideration. In all these measurements, we make use of the fact that the phase relations can be only in phase or in antiphase, which give distinctly different resultant voltages.
To phase the secondaries, measurements can be made in exactly the same way. One winding is marked arbitrarily, the other connected to its other end, and the voltage measured to the open terminal. The secondaries can be phased relative to the primary just as if they were more primary windings, provided low voltages are used and the turns ratio taken into consideration. In all these measurements, we make use of the fact that the phase relations can be only in phase or in antiphase, which give distinctly different resultant voltages.
Relay 5V
Hi, I have a bunch of relays as shown on picture. There are 5V rated.
Aim is to use it as Input selector for balanced (Relay is 2X2 type).
What kind of rectifier would be good to be prepared for runing the relays? To use separate trafo, grez and 7805 I guess would be the best option...
Hi, I have a bunch of relays as shown on picture. There are 5V rated.
Aim is to use it as Input selector for balanced (Relay is 2X2 type).
What kind of rectifier would be good to be prepared for runing the relays? To use separate trafo, grez and 7805 I guess would be the best option...
Re: Relay 5V
Thanks Zen, Mod and Spavleski for answer about trafos.
Nice to have some engineers up there...
Yes it works very well (don't forget little caps accross relay coil and protection diode).
Although I have heard that switching behaviour should be better if you use sistors to control the relay. You can use for instance some transitor arrays (most have protection diodes).
(But sure you certainly already know that)
manu
Thanks Zen, Mod and Spavleski for answer about trafos.
Nice to have some engineers up there...
spavleski said:
Yes it works very well (don't forget little caps accross relay coil and protection diode).
Although I have heard that switching behaviour should be better if you use sistors to control the relay. You can use for instance some transitor arrays (most have protection diodes).
(But sure you certainly already know that)
Jacco : is there any parts-type or brand on this planet you don't know or never heard about?
manu
boyz - ya both nutz ( yakk wonder - Jaccovitty isn't nutz , in this occasion ?!) ......
looking for schematic for implementation of few relays?
sec-graetz-1000uF-7805-10uF - selector - relays ;
each relay have just diode across coil ;
entire relay psu floating ;
what's fuss?
or I'm missing something ,as usual ?
looking for schematic for implementation of few relays?
sec-graetz-1000uF-7805-10uF - selector - relays ;
each relay have just diode across coil ;
entire relay psu floating ;
what's fuss?
or I'm missing something ,as usual ?
to understand why we need them + floating (most probably over the ground because of the avoiding inducing any hum...