
Loftech TS-1 Schematic
Loftech TS-1 Schematic Large Format jpg: https://www.ka-electronics.com/images/j ... _Large.jpg (2MB)
Loftech TS-1 Schematic pdf: https://www.ka-electronics.com/images/p ... ch_TS1.pdf
Q1, Q2, and Q4 serve as a pulse doubler to count every zero crossing so the frequency counter can update frequency every half second, instead of counting for a full second, so twice as fast and unrelated to the dB display.pascal.verdet wrote: ↑Thu Nov 02, 2017 9:12 amStudying this schema. I have simple question...
the MM74C926 is a 4-digit counter ... I understand how it works in frequency counter,
But, could you explain how do you relate the relative dB level, and its display ?
there is Q2,Q3 and Q4 act as saw tooth integrator ?
Thanks,
There is only one input audio path...pascal.verdet wrote: ↑Fri Nov 03, 2017 6:54 amMany thanks JR.
Since dB and frequency are common input J1,
Is this the same path for the two functions, or is the difference in operation just made by the S2 switch ?
the 4017 cmos dividers generate a time base by dividing down the mains frequency. Probably gated at 1/2 second rate.
Pin 12 of 74C926 are the clock input.
Secret?What is the secret to differentiate the audio level, and the frequencies?
Those 3 op amps are the function I described yesterday (sawtooth generator for dB counter.) The mV level log of the audio dB goes into pin 10 + input. The R to ground from - input pin 9 creates a linear current draw that charges capacitor C9 up or down for + or - dB voltage input.What is the exact role of the three op amps (U1 10,9,8 U1 3,2,1 U2 3,2,1 )in upper middle schema, it's just for auto scale, or anything else
Pascal
I saw a lot of TS-1's in the field that had multi-turn pots installed for that reason.In hindsight putting a frequency counter on the output of a sine wave generator that covered from <20 Hz to >20kHz with one knob was inviting a lot of disappointed customers trying to dial in exactly 1,000 Hz and getting a couple Hz one side or the other.
A later version after Gold Line took it over added a fine frequency trim pot...mediatechnology wrote: ↑Fri Nov 03, 2017 10:51 amI saw a lot of TS-1's in the field that had multi-turn pots installed for that reason.In hindsight putting a frequency counter on the output of a sine wave generator that covered from <20 Hz to >20kHz with one knob was inviting a lot of disappointed customers trying to dial in exactly 1,000 Hz and getting a couple Hz one side or the other.
For years the owner of Gold Line (Marty?) would brag to me at trade shows about how many he shipped, until he realized how much it irritated me. In fact I probably had to tell him. IIRC when I mentioned royalty he puckered up and changed the subject.
Just about every tech shop I visited in my travels had a TS-1.
It's definitely a classic.
I wonder how many have been made.
Why not ? There is more idea in two headsMaybe I will have to tell you exactly how to do this since I have only been thinking about this for more than 3 decades.