NPN power type. When

23. Select two of the 1uF electrolytic capacitors and solder the ground leads together.Install them as C3. Bend the ground leads away from U1.

24. Install C1, the remaining 1uF capacitor. The positive side should be facing R5.

25. Install the Benchmark BQ2003 IC. Notice that one end of the chip is marked with a dot, notch, or band. Be sure to orient this end as shown in the parts diagram. Pin 1 is located directly below the notch when the IC is positioned so that the notch is to the left. If you prefer to use an IC socket, you may install one if you wish. Be aware, however, that our techs find more repair problems due to sockets than due to chips burned out from overheating with a soldering iron. Be extra careful not to “bridge” the printed circuit traces together.

25a. On the bottom side of the board, install a short piece of insulated wire between pins 1 and 8 of U1. Be sure to select the right pins.

26. Install R5, 1K ohm [brown-black-red].

27. Install transistor Q3, the

NPN Power

Heat Sink

installing, be sure to form the

Tab

leads as shown to allow an

easy fit. Usually it is easier to

mechanically mount the

component with its heatsink

and then solder the

connections. Install the screw through the heat sink and the component. Tighten the nut securely.

28. Install D2, 1N4148 type diode [glass case with dark band]. Be sure to orient the banded end as shown in the parts diagram.

29. Install D4, 1N4148 diode. Watch that polarity! See the parts diagram for proper placement.

30. Install R22, 10 ohm [brown-black-black].

31. Install R10, also 10 ohm [brown-black-black].

32. Install D7, 1N4148 diode [glass case with dark band]. Be sure to observe the correct polarity.

You’ve just completed the constant current battery discharging portion of the circuit. This section, when initiated, will discharge the battery at a constant rate until the Benchmarq IC senses that the cell voltage is low enough for a complete recharge. Recheck your work for any solder “bridges” (especially on the IC) or incomplete solder connections. A bright light and a magnifying lens can be helpful for this.

We’ll continue building the final section of the Doctor NiCad circuit, the voltage sense inputs and voltage “divider”. Notice the resistor ladder in the schematic diagram. By configuring the switches to the proper number of cells in the pack, we “divide” the battery input voltage by the number of cells

DN1• 14

DN1 specifications

Ramsey Electronics DN1 is a versatile and compact digital audio transmitter that caters to a variety of audio transmission needs. It is designed for hobbyists, educators, and DIY enthusiasts looking to create their own wireless audio systems. The DN1 offers a reliable solution for transmitting audio signals over short distances without the clutter of wires.

One of the main features of the DN1 is its ability to transmit audio in the FM band, which provides clear sound quality and minimizes interference. The device operates at a frequency range of 88 to 108 MHz, allowing users to choose the optimal frequency for their specific environment. This adaptability makes it suitable for applications like personal broadcasting, classrooms, or small events.

The DN1 is equipped with a simple-to-use interface, featuring adjustable audio input levels and an LED indicator for power and modulation status. It supports both mono and stereo audio inputs, making it a flexible option for various audio sources. Users can connect the transmitter to devices such as audio players, microphones, or computers, which allows for seamless integration into existing setups.

Another significant characteristic of the DN1 is its compact and lightweight design, making it easy to transport and mount in different locations. Its robust construction ensures durability, making it ideal for both indoor and outdoor use. This makes the DN1 an excellent choice for users who need a portable solution for DIY projects or presentations.

The device operates on a low-power consumption model, which is not only environmentally friendly but also cost-effective. It can be powered by a standard 9V battery or an external power supply, adding to its convenience and versatility.

In terms of performance, the DN1 boasts a transmission range of several hundred feet in optimal conditions, ensuring that audio signals remain strong and consistent even in larger areas. This range, combined with its ease of use, makes it an appealing option for those looking to broadcast audio without the limitations of wired connections.

Overall, Ramsey Electronics DN1 stands out as an innovative transmitter that brings together user-friendly features, excellent audio quality, and practical design. Whether for personal use, educational purposes, or event hosting, the DN1 meets the demands of modern audio transmission needs, allowing users to experiment and expand their audio capabilities with ease.