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Sunday, January 24, 2016

Drive or Fire Thyristors SCR with Pulses

message: Hi, i'm looking at building a power supply 0-35v ,0-100A adjustable cv and cc. I stumbled across your circuit drive-scr-thyristor-with-555 is there a link to describe what phase logic is required to complete the basic design ?

What would the cost be to supply me a working design based on thyristor control ? my use is for electroplating, i'm not trade, but an enthusiastic amateur Kind regards

SA - USA - 2010

I will not be able to supply prototypes or make one for you. I could help with the system design. Electroplating Systems can be made with Thyristors or MOSFETS.

Thyristors, SCR, Triacs are driven by Pulses. The pulses must have adequate current and voltage levels. This depends on the Power of the device and see in the specs.

Unlike Power Transistors that need continuous bias to keep it ON, these devices just need to be Fired and may need a Isolation Pulse Transformer too. MOSFETS may need a continuous bias and very less drive current, but the ON pulse must overcome the gate capacitance.


Tuesday, January 19, 2016

Speech Recorder and Sound Syntheizer

I needed some help with available ics to build a small sound recorder able to hold about 120 seconds of audio, preferebly voice. I managed to find one that uses an ISD25xx series ic, which is not available within this region.

mail from RT

Look at these pages......

Speech recognition using HM2007

"Isolated speech recognition systems can just handle words that are spoken separately. This is the most common speech recognition systems available today."

Speech Recorder and Sound Syntheizer

Paradoxical Sound Syntheizer

"The main property of paradoxical sounds is that their frequency do not change when you go an octave higher. This property is achieved thanks to an appropriate spectrum modelling."

A Digital Speech Synthesizer, the S3610 LPC-10

"Such sound-storing and playback chips are known as digital synthesizers, and they have been around since 1978, when Texas Instruments introduced the first single-chip speech synthesizer. TI's creation was first used in a company product called "Speak and Spell" - a toy that caused quite a stir and became very popular."