Refurbished Working 1960's Heathkit EC-1 Educational Electronic Analog Computer For Sale
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Refurbished Working 1960's Heathkit EC-1 Educational Electronic Analog Computer:
$2999.99
Refurbished Working 1960's Heathkit EC-1 Educational Electronic Analog ComputerHeathkit EC-1 Analog Computer: All Original, Tested, Mostly Working (Op Amp #8 Faulty)
This EC-1 was carefully brought back to life and tested. Everything works and calibrates except op amp #8. All known flaws are listed below.
The case and inside was throughly cleaned. The EC-1 will come with 17, brand new, banana plugs.
The computer is being sold AS-IS with NO RETURNS.
Originality:
The computer is completely original. No restoration was done beyond cleaning the switches and pots. All original capacitors are still in place.
Cosmetic Condition:
Very nice overall, with only light scuffs and small dings here and there and a few very small spots of rust.
Known Issues:
Op amp #8 does not work. Its tube socket shows abnormal voltages. Swapping in a known-good 6U8 made no difference, so the fault is elsewhere in the #8 circuit, not the tube. It cannot be calibrated. I've put the one leaky 6U8 found during testing in this socket so it's easy to identify.
Original capacitors should be replaced soon. They work now, but given their age they should all be replaced before long-term use.
One OB2 voltage regulator reads low at 104V. The other two are in spec at 108V.
Some pots are stiff even after cleaning and should eventually be replaced.
Testing Performed:
Before power-up: Power supply capacitors checked for shorts and opens. All tubes tested on a B&K 747. All passed except one leaky 6U8.
Power-up: Brought up slowly over several hours on a Variac with a 60W light bulb current limiter. No shorts were found.
Voltage checks: Tube socket test points more or less match the assembly manual specs (page 36) everywhere except op amp #8.
Calibration: The manual's full calibration procedure was completed successfully on every op amp except #8.
Power supplies: All three variable DC supplies adjust through their full 0–100V range.
Oscillator and relay: The oscillator works and the relay cycles with an audible click. The rate is adjustable.
Cleaning: All pots and switches cleaned with DeoxIT D5.
Tubes: All tubes were tested and are in good working condition.
- Design: Unlike modern binary digital computers, it uses continuous voltage levels to represent data rather than 1s and 0s.
- Core Components: Contains nine vacuum-tube-based DC operational amplifiers (using 6U8 tubes), five coefficient potentiometers, and three initial condition power supplies.
- Repetitive Operation: Features a built-in multivibrator/oscillator cycling relay contacts at 0.1 to 15 operations per second to repeatedly run calculations for display on an external oscilloscope or chart recorder.
- Physical Specs: Weighs about 46 lbs (21 kg) and measures roughly 50 cm wide by 38 cm high.
- Use Case: Widely used in universities and industry during the early 1960s to teach engineering students how to model physical systems and solve differential equations.
- 6U8 / 6U8A (Triode-Pentode): This is the most crucial tube type in the unit. Each of the 9 bare-bones operational amplifiers uses a 6U8 or 6U8A tube (a triode and a pentode housed in a single envelope).
- Voltage Regulator (VR) Tube: The power supply uses a standard cold-cathode gas-filled voltage regulator tube (typically an OA2 or OB2 depending on the specific revision or section, often designated as a generic VR tube in the manual) to regulate the -150V bias supply.
- NE-2H (Neon Glow Lamps): The level shifter circuit at the output of the op-amps utilizes two NE-2H neon bulbs per amplifier to safely drop the voltage down to the ±60V range for the front-panel banana jacks.
- Banana Jacks / Binding Posts: If you are replacing the faded or broken jacks, standard 4mm uninsulated or insulated panel-mount banana jacks fit perfectly.
- FT-241 Crystal Sockets: The front "programming/personality modules" originally plugged into slots meant for WWII-surplus FT-241 radio crystal pins. Because these original components are incredibly rare, restorers often custom-fabricate new modules using 2.4mm brass rods or vintage octal tube socket pins.
- Resistors: The original schematic specifies standard 1/2-watt carbon composition resistors for general layout, alongside high-precision 1% tolerance resistors for the operational circuitry. Modern 1/2W metal film resistors are excellent, stable replacements.
- Capacitors: If your unit has a 60Hz hum or won't hold initial conditions, the original paper and electrolytic capacitors are likely degraded. Replace them with modern axial electrolytic capacitors rated for at least 450V to handle the high B+ voltages (≈ 240V to 300V).
If there is an issue with the product then email me first.Don't revert to leaving undesirable response. The best way is to simply communicate with an email. I work with all my costumers to try and make it right.
I work as high school teacher and the only days I can ship are a few days on Monday, and every Tuesdays and Thursdays. I don't ship on the weekend because my box store is not open on those days, I am busy testing and posting computers for sale, and I want to spend some time with my family. Thus, I place a "3 days to ship" to accommodate these issues.Thank you for your understanding.
I only use Global Shipping Service on International Order, no exceptions.
I will ship to Hawaii, Alaska, PO Boxes, and PR, even though I have a block on these areas, but they will be subject to paying exact shipping cost that will be calculated. Please ask prior to purchasing the computer.
policies leave me with no choice but to mark each of my sales with a “no return” policy. This is being done to protect me against returns such as (buyer’s remorse). After using the item for days and weeks, the buyer can submit a return and is not obligated to reimburse the seller for shipping charges and I have to pay for shipping charges back. Even though it is marked a “no return, “a buyer can still submit a return if the item was not as described or the item was damaged during shipping. Also, I do not need an policy to do what is right and accept the item back if it wasn’t as described or damaged during shipping. Keep in mind, that I mainly sell vintage computers and vintage computer accessories. That said even though the box/item may not show damage, the internal mechanism may have been damaged or jarred from a rough truck and/or plane ride. I will work with ALL my customers to resolve the problem. Recently, I have had to take back items where the buyer didn’t check with mom/dad, husband/wife, or God prior to buying and did a return. forced me to take the item back. Personally, I do not think that this is an acceptable way to return items. Many of the sellers on here are just trying to provide for their families and this kind of previous return is not fair to the seller. We are not Walmart or Costco that cannot absorb these financial damages. Again, I will work with all my costumers to ensure that they are happy with the item they purchased. Thank you for your patronage.
Documentation
- Customizing Knoppix
- Remastering Knoppix
- Hard Drive Install
- Knoppix Cheat Codes
- Install Knoppix How-To