HD-1410 is quiet popular iambic keyer which is manufactured around 1970’s by Heathkit. The original HD-1410 keyer is designed using 5 commonly available 74LS series TTL ICs and 8 transistors. Other than iambic operation it has an option to adjust sidetone frequency and support for (external) single-paddle key unit.
In this project we redesign original HD-1410 electronic keyer with today’s commonly available components. In this new design the key components which we replace are transistors, diodes and power supply section of original HD-1410 circuit. Most of the NPN transistors in original design are replaced with KSP42 and KSP10 transistors, and all the PNP transistors are replaced with KSP92 transistors. To keep everything simple we also use same TTL chip-set with this new design.
Testing of sensors with RS485 using PC without proper interface is not possible. Since RS232 interfaces are very rare, the interface should be hooked to USB. The interface between USB and RS485 can be soldered with one of the many FTDI interfaces with added RS485 driver, or bought as assembled module. There is always the third option. I made it from scratch.
[This Old Tony] teaches us how to make springs on a lathein this video done in the style of How It’s Made. Mixed in with snark, in his usual style, is a lot of useful information.
The Machinery’s Handbook certainly has all the information one would need to design the basic spring shapes, but it’s not always necessary. [Tony] points out that cheating is entirely acceptable. For example, if you need a spring that’s close to the dimensions of a standard spring, simply copy over the values from the standard spring. He explains all the terminology needed to decrypt the pages in your engineering tome of choice.
He shows the basics of winding a spring on a mandrel (or that round metal thing, if you want to use the industry term). First wind the inactive coils, then set your lathe to the desired spring pitch. Engage it as if threading, then disengage and wind the final inactive coils. A quick trip to the sander squares the ends of a standard coil spring. However, the tools can also be used to make torsion springs, or even exotic combination springs.
For a good… educational laugh, watch the whole video after the break.
If you are of a certain age you may have worked in an office in the days before the computer revolution, and the chances are that in the corner of your office there would have been a teletype machine. Like a very chunky typewriter with a phone attached, this was an electromechanical serial terminal and modem, and machines like it would have formed the backbone of international commerce in the days before fax, and then email.
Teletypes may have disappeared from the world of trade, but there are a surprising number still in private hands. Enthusiasts collect and restore them, and radio amateurs still use digital modes based on their output. The problem facing today’s teletype owner though is that they are becoming increasingly difficult to interface to a modern computer. The serial port, itself an interface with its early history in the electromechanical world, is now an increasingly rare sight.
In his design he’s had to solve a few problems related to such an aged interface. Teletypes have a serial output, but it’s not the TTL or RS232 we may be used to. Instead it’s a high-voltage current loop designed to operate electromagnets, so his board has to incorporate an optocoupler to safely isolate the delicate computer circuitry. And once he had the teletype’s output at a safe level he then had to translate its content, teletypes speak 5-bit ITA2 code rather than our slightly newer 7-bit ASCII.
The result though is a successful interface between teletype and computer. The former sees another teletype, while the latter sees a serial terminal. If you have a teletype and wish to try it for yourself, he’s released the source code in a GitHub repository.
PCB Power connection solution from Würth Elektronik, Link here
As a solder free fastening technology, press-fit technology frequently offers an attractive alternative to simple soldering technology. An effective electrical press-fit connection is created by pressing a pin into the plated through hole of a circuit board and – as part of cold welding process – generating a gas-tight electrical connection.
The trough-hole plating for a press-fit system is essentially made in the same way as are the holes for accepting components for THT soldering. Thus there are no changes required in the pcb manufacturing process. One outstanding characteristic of the press-fit system compared to the soldering system is that it produces not only an electrical connection but also an extraordinarily strong mechanical connection between the inserted components and the PCB.