Product Overview
Motorola MC838P Decade Counter - 15V High-Threshold Logic, One Chip in Its Factory Foam Carrier
Condition
Unused, New Old Stock in the original Motorola packaging. You are buying one chip. Three are in stock, and the group photo shows all three together for an honest reason: the pieces are not identical. Each one carries its own date code, and the packaging differs from piece to piece. One carrier is open and unlabeled, with the device sitting in the recess and its gold-plated leads bright, straight, unclipped, and free of solder or socket marks. The second carrier still wears the blue Motorola Semiconductor Products Inc. label printed 5005 East McDowell Road, Phoenix, Arizona 85008, with the device visible through the window between the label bands. The third is labeled as well, but the window film is torn where it was opened, so only a dark sliver of the device shows. One photographed body carries a light grey crusted deposit at the end where the epoxy sits against the foam. Visual inspection completed with no issues noted. We do not assign a particular carrier or date code to an order; order the quantity you want and we pull from the three on the shelf.
Same or next business day shipping from our Idaho warehouse. Honest pricing, no nonsense.
Online since 1999. We are here for our customers, with a no-hassle satisfaction guarantee.
Product Overview
The Motorola MC838P is a monolithic silicon decade counter from the MC800 series High-Threshold Logic family, built to divide an input by ten and hold its count in electrically noisy places where ordinary 5V logic would pick up trash and miscount. It runs on a nominal 15V supply with a switching threshold near 7.5V, trading switching speed for noise immunity, which is exactly the bargain a mill floor or a machine tool cabinet wanted. The package is a 14-pin plastic DIP with gold-plated leads, a reliability choice common in industrial parts of the era and plainly visible in the photographs. It is not a drop-in for a 7490 or a CMOS 4017; the MC838P belongs in 15V HTL designs and nowhere else. The chip you buy arrives in its original Motorola foam carrier, and the three on the shelf differ in date code and in label condition, which is what the group photo is there to show.
Key Features
- Divide-by-10 (decade) counting function
- MC800 series High-Threshold Logic (HTL)
- Nominal 15V operating supply
- High noise immunity with approximately 7.5V logic threshold
- Typical propagation delay 100ns to 200ns
- Maximum clock frequency approximately 1MHz to 3MHz
- Power dissipation typically 150mW to 200mW
- 14-pin plastic DIP package
- Gold-plated leads, bright and straight on the two pieces visible in the photos
- Sold as one chip per order; three are in stock if you need more than one
- The three are not identical: each has its own date code, and packaging differs piece to piece as the group photo shows
Applications
- Maintenance electrician rebuilding an HTL control card in a mill or press line where the counter stage quit
- Machine tool restorer keeping an early CNC timing chain period-correct instead of grafting on a 5V conversion
- Museum or instrument technician bringing a vintage HTL lab counter or trainer back to working order
- Industrial electronics builder prototyping on a 15V HTL bench where noise immunity matters more than clock speed
Frequently Asked Questions
Can I drop this into a 7490 or CMOS 4017 socket?
No. The MC838P is a 15V High-Threshold Logic device and is not pin-compatible with 5V TTL or CMOS counters. Putting 15V into standard logic will destroy it. Match the original HTL design and check the board schematic before you order.
The photo shows three chips. How many do I actually receive?
One. This listing sells a single MC838P, and three are in stock, so if you want two or three, raise the quantity at checkout. The group photo is in the listing so you can see that the pieces are not identical: each carries its own date code, one carrier is open and unlabeled, two still wear the blue Motorola label, and one of those has its window film torn where it was opened. We cannot promise a specific date code or a specific carrier with an order, so if your build needs one particular code, ask us first and we will read what is on the shelf.
Why are the leads gold plated?
Gold resists oxidation, which is why these leads still look bright after a long stay in foam. It keeps solder wetting and socket contact dependable on parts that sat in stock far longer than anyone planned. Nothing in the photos shows tarnish, bent pins, or trimmed leads.
Is it worth using in a modern 5V or 3.3V project?
Generally no. The supply voltage and logic levels do not line up with modern parts, and level-shifting a 15V HTL counter into a microcontroller build is more trouble than a current-production counter is worth. This chip earns its place in restoration and maintenance of original HTL equipment.
I need one counter for a board repair, not a bag of them. Can I buy just the one?
Yes, and one is exactly what this listing sells. An HTL repair usually needs a single counter stage, so one chip is the default; if the job wants a spare or a matched pair, set the quantity to two or three and we will pull that many from the shelf. The alternative elsewhere is a forced lot of twenty-five obsolete logic chips, which is a drawer full of parts you did not want. The three here differ in date code and packaging as the photo shows, and no specific piece is promised with an order. Shipping is $8 flat rate and free once your order passes $28, and orders leave our Idaho warehouse the same or next business day.
Motorola shipped these one to a foam block, each under its own blue Phoenix label, back when a decade counter was worth that kind of packaging. Three of those blocks survived, no two of them alike, and one of them leaves here for your bench to go back where 5V logic would lose the count.
