This is about as close as you can get to a real vintage Pultec EQP-1a. Built from the original Pulse Techniques Pultec schematic with the layout designed around modern replacement parts (filter caps and trannys); and utilizing best practices regarding lead dress and component placement. Parts cost is around $1265 USD. I now offer a complete Pultec
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EQP-1a Kit for $1645 that includes upgraded filter section capacitors, a new master layout and 500 high-resolution assembly photos. The Pultec`s original Triad HS-56, HS-29 and Peerless S-217-D transformers would have been great, but sourcing them all is very difficult, primarily because of the rarity of the Peerless S-217-D output tranny. As the Peerless is so exotic, I didn`t really care about sourcing the input and interstage trannys because without the S-217-D, the point seemed moot. On the plus side, modern EQP-1a equivalents from Sowter have a much smaller footprint which facilitates a 2u rack chassis if desired - and the quality is artisan. For those inclined, the original Chicago PCC-55 power tranny does appear on eBay with some frequency and modest pricing. For the inductor, I chose Cinemag`s Pultec replacement CML-150T. Build notes: I separated the EQP-1a`s amplifier section from the Pultec passive filter circuit by way of two separate turret boards. The amp section is on the rear panel. This provided a nice way to route the filament wires in the upper corner of the rear of the chassis to keep things quiet as well as keeping the HT stuff away from the passive. One particularly interesting thing is that the 6x4 rectifier runs off the same 6. 3V filament as the 12ax7 and 12au7 tubes, and the power transformer rectifier 5V winding only powers the lamp. I ended up moving the interstage and input transformers to the...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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