In a piezo-resonator in which the resonator cavity is coated with a resinous insulator, a lip which defines a ridge for the mounting of the terminal strips to the resonator is fused to the outer surface of the strips. The seal produced thereby prevents resin from invading the resonator cavity during the resin coating process.

A piezoelectric resonator which can be used as part of a piezoelectric component prevents self-welding of electrodes provided on the surface of a piezoelectric and which include silver with silver coated terminals with which the electrodes abut by forming high fusion point metals on the electrodes. The high fusion point metals include Ni, Cr, W, Ti, Mo, Ni--Cu (monel) or their alloy. The thickness of the high fusion point metal is preferably less than about 1/10 of the thickness of the electrode or less than 1 .mu.m.

A resonator assembly having a base and a cap provided with cooperating notch and projecting terminal retainer structure serving to retain the terminals of the spring contacts in centered disposition within the assembly and further serving to retain the cap to the base in assembled disposition. The notches are caused to have a width slightly greater than that of the terminals to permit facilitated inward movement of the terminals into the notches in the assembly procedure. The base is further provided with at least one securing recess and the cap is provided with a corresponding number of securing projections fitted one each into each securing recess for further securing the cap to the base. The sidewall of the base may be enlarged to accommodate the securing recesses therein.

An electric terminal particularly designed to establish circuit connection with a piezoelectric ceramic disc employed in a smoke detector alarm horn. The electric terminal comprises a pair of joined and spaced sidewalls disposed in a generally parallel relationship with respect to each other, a contact-beam support wall joining the pair of sidewalls, and a resilient, cantilevered contact beam having a first curved section fixed to the support wall and having a generally straight section formed with a pointed electrical contact adapted to engage the piezoelectric ceramic disc or other electrical load.

An improved piezoelectric crystal unit provides a housing, a piezoelectric crystal element, and oppositely disposed mounting means for suspending the crystal element within the housing. A first set of three cradle means and a second set of three cradle means engage opposite faces of the crystal element. Each of the first set of cradle means contains a face member disposed adjacent the first face of the crystal element and an edge member disposed adjacent the peripheral edge of the crystal element and each of the second set of three cradle means contains a face member disposed adjacent the second face of the crystal element and an edge member disposed adjacent the peripheral edge of the crystal element. Integral with each of the first set of cradle means are elongated resilient legs exerting uniform pressures on one face of the crystal element and integral with each of the second set of cradle means are elongated resilient legs exerting uniform counterbalancing pressures on the other face of crystal element. The housing provides a nest and contains a rim having a pair of notches and an end wall having an embossed center portion. A cover having an end wall with an embossed center portion interfits with the housing to enclose the nest. A first circular center section engages the embossed center portion of the housing and a first terminal means integral with the circular center section extends through a first one of the notches to align the first set of three cradle means within the nest. A second circular center section engages the embossed center portion of the cover and a second terminal means integral with the second circular center section extends through a second one of the notches to align the second set of three cradle means within the nest.