• audio booster amps for radios, walkmans etc. • replacement amplifiers • high sensitivity long distance listening amplifier for ‘big ear super sleuth’ snooping! • mini pa systems • telephone amplifiers • intercom systems • anywhere some quick audio amplification to speaker level is needed keep seve...
Introduction to the bn9 the bn9 is a high gain miniature amplifier with all sorts of possible applications, limited only by your imagination. Its small size and economical price make it a useful addition to many projects and re- pairs. The bn9 has an amplification gain factor of 3000 with as much as...
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) ❒ 1 lm380 audio amp...
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 mechani...
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 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 designate...
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 ...
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 zillio...
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. Check...
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 b...
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” listenin...
2. Intercom components required: • dpdt switch (momentary most practical) • two 8 ohm speakers • your choice of enclosures in out low gain bn-9 remote local 3. Mini public address amplifier components required: • 8 ohm pa speaker or horn speaker • 5k to 100k potentiometer • electret microphone or ot...
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 to re ce ive r in o u t 1 0 l o w g a in b n-9.
P ro b e 2 0 0 v in o u t 5. Signal tracer test probe components required: • .01uf ceramic capacitor rated at at least 200v for tube circuits • 5k to 100k potentiometer • shielded test probe with ground clip • 8 ohm speaker or earphone other applications with a little ingenuity you can use the prece...
The ramsey kit warranty please read carefully before calling or writing in about your kit. Most problems can be solved without contacting the factory. Notice that this is not a "fine print" warranty. We want you to understand your rights and ours too! All ramsey kits will work if assembled properly....
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