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ET3400 Address Decoder

Address decoder for use with the Heathkit ET3400 microprocessor trainer. A 74LS30 eight input NAND gate and a 74LS20 4 input NAND gate are used to decode the 16 bit address lines on the Motorola 6800 microprocessor.

The 74HCT138 three to eight line decoder uses the 16 address lines along with the R/W and VMA02 clock line to decode locations #0FFF to #7FFF.

The circuit below (2nd Photo) uses a 74HCT573 eight bit ‘D’ latch to store / output data from a specific address location.




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Celestron XCel LX Eyepiece – Barlow

Celestron XCel LX Eyepiece

60 Degree Field of View

Six Element Design

Fully Multicoated

Twist-Up Eyecups

Luminos Barlow Lens

2.5x Magnification

4 Element Apochromatic Design

Brass Compression Ring

28mm Clear Aperture




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ET3400 Microprocessor Trainer

The ET-3400 Microprocessor trainer uses the Motorola 6800 or 6808 microprocessor and along with the EE-3401 Heathkit Continuing Education ‘Microprocessors’ learning course, allows one to learn the structure and the programming of the 6800 (6808) microprocessor.

The 6800 is an 8 bit microprocessor. This means the data bus can handle 8 bits of binary information. The trainer allows the user to program the 6800 in machine language which is the most basic way possible. It is a flexible, general purpose microprocessor breadboard.

The ET-3400 has a six digit hexadecimal display for reading out memory addresses, their contents, and register contents.

Microprocessor address bus, data bus, control lines, and other associated signals are buffered and terminated on front panel connectors. The trainer also has eight individual LED’s that can be used to monitor logic states and eight individual data switches to supply binary words for the breadboard circuits.

Built in power supply voltages of +5VDC and also +/- 12VDC are connected to front panel connectors.




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DRV8834 Breakout PCB

This is a breakout PCB for the Texas Instruments DRV8834 for bipolar stepper motors. The DRV8834 has two H bridge drivers that can be used to drive two DC motors or one unipolar stepper motor. It has a supply voltage range of 2.5 VDC to 10 VDC with a continuous current rating of 1.5A.

The DRV8834 also has internal shutdown features such as overcurrent protection, short circuit protection, undervoltage lockout, and over temperature protection.

Pololu DRV8834 Breakout PCB



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Astro-Physics Traveler

The Astro-Physics Traveler is a 105mm (4.1 inches) aperture apo refractor telescope with a focal ratio of f6. The telescope has a black finished aluminum tube with an overall length of 19 inches and a weight of 9 pounds.

This is a very well made (in USA) telescope that will give excellent views of the moon and planets and wide angle views of other celestial objects. This telescope will also give excellent views of daytime objects.






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