lnstituto
Odon Sanchez de lta and Manuel Urquiza Tecnologico de Monterrey,
Monterrey, Mexico
I
I
A Simple Direct Current Source for the Laboratory
with a core made of sixteen 31/2-in. iron nails. The choke has the following characteristics: 14 Hys, 300 ma, 60 ohm. It can be replaced by Type C-2308, Allied Radio (8 Hys, 300 ma, 8 ohm).
We have built a simple apparatus for the conversion of ac to dc which can be made easily and cheaply. Similar devices have previously been reported.' I n the present case, the circuit is simple and more stable. ~ h e b r e s e n apparatus t could be employed as a source of current in determinations of transference numbers by the Hittorf method in which the amount of electricity is measured accurately by a coulometer. The circuitZ and its parts are indicated in the diagram. The choke is made of No. 26 copper enamel wire (13,000 turns)
-F, 9
AC
