Filter
Top Products
HR20• 17
SA602 audio output at the volume control, and switch in a pleasant oscillator
pitch (keying sidetone) which is amplified to listening level by LM386. The
Ramsey Electronics Universal timer kit No. UT-5 is easily adapted as a
sidetone oscillator.
• SPEAKER OPERATION
A fifty cent, two inch diameter speaker, lying naked on your workbench will
give you a fair test of the speaker output capability. Speaker quality and well-
designed enclosures have their clear purposes! A reasonable speaker in a
box delivers a pleasant listening volume. On the other hand, the LM386
indeed can deliver more audio output punch than is developed in our HR-
series kits. For example, our FM receivers, using the same LM386 audio IC,
deliver more volume. These receivers, however, take advantage of IF
amplifiers, drift-compensation and crystal controlled oscillators built into mass
production sophisticated FM receiver ICs. A heavier drain on the HR20’s
battery by stronger audio will quickly result in chirpy signals and oscillator drift
as well as the need for frequent battery replacement. Remember the SA602
circuits similar to the Ramsey HR-series generally call for sets of C or D cell
batteries! For Experienced Builders more information regarding audio output
is in the general notes.
The simple design of the audio stage of the Ramsey HR20 receiver assumes
preference for headphone or small speaker operation, low battery drain and
general economy.