Scotts Electronic Parts
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For Sale MK484 AM Radio IC
The MK484 MK-484 MK 484 is a AM radio receiver IC has automatic gain and up to 72 db gain. It is cased in a TO-92 Case looks like a transistor. The MK 484 runs on 1.1 to 1.8 volts so a single 1 1/2 volt battery will work. Also the MK-484 needs a tuning Capacitor and Ferrite Rod Coil or also known as a loopstick antenna we sell both items.
The MK484 Kits are TRF ( Tuned Radio Frequency, Tuned RF ) type receivers. This the most basic type of radio receiver with no regeneration or re-genitive feedback. The variable capacitor and antenna coil form a "Tank" circuit that tunes the radio stations frequency then the MK484 amplifies the radio stations radio frequency then "Rectifies" (Converts to Audio) it then amplifies the audio and powers the Earphone.
Yes a real MK484, not like other sites that sell MK484/TA7642. If you see this designation on other sites you are getting a TA7642 not a MK484.
I also have for sale the YS414, TA7642, UTC7642, CD7642 and KM484 (not a typo yes a KM484) sold separately at bottom of this page if you are looking for one of these instead of the MK484.
The YS414, TA7642, UTC7642, CD7642 and KM484 are the same as the MK484 only different manufactures.
I do not ship equivalent parts if you order a MK484 I ship a MK484 not one of the others.
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Below is a link to MK484 schematics for the MK484 kits.
Kit Number 3 has a coil with a center tap. The center tap should get better selectivity and decreased chance of overloading the IC. Or can be connected using the end of the coil, this lets you experiment with coil taps. You can also connect the variable capacitor Pin "A" to Point 1 and the MK484 input Point "3" to Point 1 also and leave the end of the coil Point "2" unconnected to cover the mid AM band from about 740 KHz about 2.2 MHz just a little into lower shortwave bands.
The difference in Kit 3 and Kit 4 is the coil supplied, I also have 608uh Round rod coil with no taps that be swapped for the others if you want no taps on the coil just send me an email stating you want the 680 Round Rod Ferrite Coil. This keeps me from making another kit number.
Any coil in any kit can be swapped out for one of the others. If you do not want the standard supplied coil that comes in a kit send me email stating the coil you want with your kit. I have 3 choices 788uh with antenna tap and center tap , 680 with tap around 470uh ( this is the standard for all the Kits but Kit number 3) and a Round Rod 680uh with no taps.
MK484 Schematic Circuit Diagram for MK484-Kit-3.pdf
The below alternate circuit diagram for the MK484-Kit-3 is to show the different RF input connection options. If you are using a different output like the 2000 Ohm headphone or the piezoelectric ceramic headphones keep the audio output the same as Kit-5 and Kit-6. This is only to show an alternate way to wire the RF input section using the 788uh ferrite antenna coil with center tap. You can try short antenna connection at 1, 2 or 3 or wrap about 5 turns of small gauge wire around the ground end of the ferrite rod and connect one end of the 5 turn coil to an antenna and the other to ground. A common ground to circuit is not needed.
MK484 Radio Kit-3 Alternate RF Input Schematic Diagram Alternate MK484 Radio Kit-3.pdf
MK484 Schematic Circuit Diagram for MK484-Radio-Kit-4.pdf
The below alternate RF input wiring diagram for the Kit-4, Kit-5 or Kit-6 with the 680uh ferrite antenna coil with a tap on it. Will have greater selectivity with a little less volume. For an antenna if you want to try one just wrap about 5 turns of small gauge wire around the ground side of the ferrite rod and connect one end of the 5 turn coil to an antenna and the other to a ground. A common ground to circuit is not needed. The MK484 over loads very easy so a long antenna might over load it and station separation will suffer. Keep the same audio output circuit for the headphone or earpiece type you are using. The changes are for only the tunning input section.
MK484 Kit-4 Alternate Circuit Schematic Diagram MK484 Radio Alternate Circuit For Kit-4-5-6.pdf
MK484 Schematic Circuit Diagram for MK484-Kit-5.pdf
MK484 Schematic Circuit Diagram for MK484-Kit-6.pdf
The PDF file below shows how to add an adjustable auto gain control to the MK484
MK484 Circuit Diagram to adjust the Auto Gain MK484AutoGain.pdf
Internal Circuit Diagram for the MK484 MK484 Internal Circuit Diagram.pdf
Any of the above MK484 circuits will work with the YS414, TA7642, UTC7642, CD7642
For Sale MK484
Parts the same as in Kit-4 below only it has different Antenna Coil.
This kit comes with (Mono 2000 Ohm High Impedance Headphones). With 1/4 plug ends.
This kit comes with a High Impedance Ceramic Headphone. Wire mono with 1/4 inch plug end cord is about 40 inches long.
The Piezoelectric functions the same as a Ceramic Earphone. The are not the homemade Headphones sold on other sites with Piezo Transducers, these were made by a Headphone Manufacturer special for me.
Order Variable Capacitors Here. The MK484 Kits Use the 60/141pf Models.
Two Sizes Ferrite Rod Antenna ( Loopstick Antenna Coils )
Picture on left Flat Rod types 5mm X 12mm X 55mm long. Two sizes 788uh Tap at center and tap about 10 turns from end and 680uh tap at 470uh. Picture on right 680 round rod 10mm X 60mm long ( about 3/8 inch X 2-3/8 long)
The MK484 Kits Use The 680uh With Tap At 470uh.
The diameter is about that of a dime.
The diameter is about that of a nickel.
Mono High Impedance Headphones with 1/4 inch plug ends. The High Impedance Headphones have an Impedance of 2000 Ohm making them ideal for the MK484 Ic or the YS414, TA7642, UTC7642, CD7642.
Mono High Impedance Piezoelectric Headphones with 1/4 inch plug ends. These headphones have an resistance of over 20 million ohms. Factory made not homemade.
Part # 1/4Jack-1, Mono 1/4 Phone Jack for my High Impedance Headphones Price $1.97 Each
For Sale TA7642
TA7642 - Radio Kit ( Same as the parts as the above MK484 Kit-4) only comes with TA7642 instead of the MK484.
For Sale YS414
YS414 - Radio Kit ( Same as the parts as the above MK484 Kit-4) only comes with YS414 instead of the MK484.
For Sale CD7642
CD7642 - Radio Kit ( Same as the parts as the above MK484 Kit-4) only comes with CD7642 instead of the MK484.
For Sale UTC7642
UTC7642 - Radio Kit ( Same as the parts as the above MK484 Kit-4) only comes with UTC7642 instead of the MK484.
For Sale KM484
KM484 - Radio Kit ( Same as the parts as the above MK484 Kit-4) only comes with KM484 instead of the MK484.
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