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Keep several of these for:
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Audio booster amps for radios, Walkmans
etc.
•
Replacement amplifiers
•
High sensitivity long distance listening
amplifier for 'Big Ear super sleuth' snooping!
•
Mini PA systems
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Telephone amplifiers
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Intercom systems
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Anywhere some quick audio amplification to
speaker level is needed
The BN9 combines a high gain transistor pre-amp with the powerful LM-380 audio amplifier for over two
watts of audio. Your choice of either a gain of 50 or 3000! Runs on 8 to 15 volts, drives any speaker from
3 to 45 ohms with less than one percent distortion.
Kit No. BN9
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Related Manuals for Ramsey Electronics BN9
Summary of Contents for Ramsey Electronics BN9
- Page 1 The BN9 combines a high gain transistor pre-amp with the powerful LM-380 audio amplifier for over two watts of audio. Your choice of either a gain of 50 or 3000! Runs on 8 to 15 volts, drives any speaker from 3 to 45 ohms with less than one percent distortion.
- Page 2 The BN9 has an amplification gain factor of 3000 with as much as 2 1/2 watts of audio power output. It can also be configured for a gain of only 50 to make it versatile for any number of applications.
- Page 3 BN9 PARTS LIST 2 .01µF ceramic disk capacitors (C1, C2) 3 4.7µF or 10µF electrolytic capacitors (C3,C4,C6) 1 100µF to 500µF electrolytic capacitor (C5) 1 220K ohm resistor (red-red-yellow) (R1) 1 10K ohm resistor (brown-black-orange) (R2) 1 NPN transistor, 2N3904 (Q1)
- Page 4 BN9 PC BOARD ASSEMBLY As you can see this is a fairly simple and straightforward project, but be careful! Don’t rush and improperly mount a part or leave long lead lengths on components. As all good technicians and experimenters know, parts must be mounted flush to the PC board. Not only for mechanical strength and looks, but also to prevent oscillation problems by long lead lengths acting as small antennas.
- Page 5 ASSEMBLY OF THE BN9 1. Orient the circuit board as shown in the Parts Layout Diagram. 2. Install U1, the LM-380 IC into the PC board, making sure that all 14 pins are in their proper holes. Also note in which direction the notch is oriented in the Parts Layout Diagram. Make sure U1 is mounted in the same way when you solder it in.
- Page 6 The following electrolytic capacitors are polarized and must be inserted with proper orientation to the polarity markings. Usually the capacitors are marked with a side stripe to indicate the negative (-) pin or rarely a plus symbol to indicate the plus side. NOTE: The Parts Layout Diagram designates the holes where the positive (+) leads go.
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Page 7: Initial Tests
INITIAL TESTS: 1. Connect up 8 to 15 volts of DC power. For simplicity use a red wire for positive (+) and a black wire for negative (-). Wait! check polarity before switching on the supply. 2. Connect any speaker ranging from an impedance of 3 ohms to 45 ohms. Speakers in the 4 to 8 ohm region are best suited for this kit and will yield the greatest power. -
Page 8: Troubleshooting
MICROPHONE AND AUDIO INPUT CONSIDERATION You may choose almost any transducer to convert sound into an electrical signal for your BN9. Some of the transducers are as follows; ceramic, crystal, dynamic, or even another speaker! You may also use audio from any other source as well (other than a zillion watt per channel power amp!) - Page 9 Problem: Output drops out and then builds up again each time volume control is advanced. Solution: You are running with too much input power. Change circuit for lower gain operation or re- duce input level. Problem: Very strong AC hum. Solution: Input may not be shielded or connected properly.
- Page 10 Solution: Motorboating is a sound like the “putt-putt-putt” of a two cycle motor boat. While it may be a novel idea for a simple kit, it’s not exactly what we have in mind here. This is usually noticed at higher audio levels due to the power drawn from the power source. The power source (such as a battery) can’t quite deliver the power needed during a peak, so the voltage “sags”...
- Page 11 BN9 APPLICATION IDEAS: 1. High sensitivity listening device Components required: Small microphone such as RAMSEY MC1, mini-electret mike. • 5K to 100K potentiometer for volume control. • 10K resistor (brown-black-orange) • .01uf Ceramic capacitor • NOTE: To make a full-performance “big ear” listening system, use a snow coaster or large plastic popcorn bowl.
- Page 12 2. Intercom Components required: DPDT switch (momentary most practical) • Two 8 ohm speakers • Your choice of enclosures • Remote Local Low gain BN-9 3. Mini public address amplifier Components required: 8 Ohm PA speaker or horn speaker • 5K to 100K Potentiometer •...
- Page 13 IN OUT Horn Speaker High Gain BN-9 4. Auxiliary amplifier for mini receivers Components required: 8 Ohm speaker • 5K to 100K Potentiometer • 10 ohm resistor • L o w g a in B N -9 O U T R e c e ive r...
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Page 14: Other Applications
BN9, being simple to assemble and operate, is an ideal choice for circuit add-ons. Ramsey Electronics offers a whole line of kits, from handy “Mini-kits” like this one, all the way up to state of the art synthesized FM transceivers and car audio amps. Call or write for our free... - Page 15 But on rare occasions a sour component can slip through. All our kit parts carry the Ramsey Electronics Warranty that they are free from defects for a full ninety (90) days from the date of purchase. Defective parts will be replaced promptly at our expense.
- Page 16 RAMSEY TRANSMITTER KITS RAMSEY AMATEUR RADIO KITS · FM10, FM25B FM Stereo Transmitters · DDF1 Doppler Direction Finder · MR6 Model Rocket Tracking Transmitter · HR Series HF All Mode Receivers · AM1, AM25 AM Transmitters · QRP Series HF CW Transmitters ·...