You may use a BC547 again if not having a BC517. Put a ceramic or film capacitor (10nF-100nF) between it's collector and base pads underneath if you will notice any chatter noise (mechanical) coming out of the relay.
I'm running into similar issues finding the BC 550 / BC517.
Right now, eBay / North American stock are what I'm limiting searches (Excluding China for one reason, other places for shipping costs).
It stings paying $8 fo a $0.25 part, but that's the best I can find.
Darlington specified for the BC517? I see Darlington, KEC, Phillips, and some cheap ones listed below what major distributors have listed for out of stock parts.
I'm making the assumption that the part numbers ending in CTA vs Bulk designation doesn't make a difference other than hoping for careful handling of the parts?
Right now, eBay / North American stock are what I'm limiting searches (Excluding China for one reason, other places for shipping costs).
It stings paying $8 fo a $0.25 part, but that's the best I can find.
Darlington specified for the BC517? I see Darlington, KEC, Phillips, and some cheap ones listed below what major distributors have listed for out of stock parts.
I'm making the assumption that the part numbers ending in CTA vs Bulk designation doesn't make a difference other than hoping for careful handling of the parts?
CTA is just about bent leads if I remember correctly. Any make will do. Its the relay coil driver, to work predictably well in this circuit it either takes an NPN Darlington or a high beta NPN like a BC547 with the help of a compensation capacitor as described in the previous post.
Step up transformer on B1 buffer
I would like to know if adding Jensen Transformers JT-123-FLPCH output as step up for a bit of gain is a problem for the Mezmerize B1?
I would like to know if adding Jensen Transformers JT-123-FLPCH output as step up for a bit of gain is a problem for the Mezmerize B1?
From the Jensen datasheet:
"This transformer is designed for high performance output stages. The 50% nickel alloy core gives it excellent distortion and level handling. It may optionally be configured for 1:2 step-up or 2:1 step-down operation. Driving signals should be free of DC and source impedance kept as low as possible."
I don't see any particular problem interfacing it with Mez DCB1, DC offset is typically very low with well matched JFETs not to saturate the transformer. Because its input impedance (Zi) is stated 712 Ω typical, use a 33 Ω output resistor in the Mezmerize instead of 220 Ω. That's working like the X1 isolation in Jensen's example schematic. There is about 35 Ω intrinsic JFET output impedance added to that. Use a 68 Ω in X2's place. Keep the DCB1 board output and the Jensen near in same box with short cables.
"This transformer is designed for high performance output stages. The 50% nickel alloy core gives it excellent distortion and level handling. It may optionally be configured for 1:2 step-up or 2:1 step-down operation. Driving signals should be free of DC and source impedance kept as low as possible."
I don't see any particular problem interfacing it with Mez DCB1, DC offset is typically very low with well matched JFETs not to saturate the transformer. Because its input impedance (Zi) is stated 712 Ω typical, use a 33 Ω output resistor in the Mezmerize instead of 220 Ω. That's working like the X1 isolation in Jensen's example schematic. There is about 35 Ω intrinsic JFET output impedance added to that. Use a 68 Ω in X2's place. Keep the DCB1 board output and the Jensen near in same box with short cables.
Attachments
Thanks
Thanks,
I'm still playing with the output resistor but the sound is amazing. Just the right amount of gain and a bit of tubiness, less antiseptic. I can go back to the
razor accurate stock B1 when I want to.
This stuff just doesn't get old.
Thanks,
I'm still playing with the output resistor but the sound is amazing. Just the right amount of gain and a bit of tubiness, less antiseptic. I can go back to the
razor accurate stock B1 when I want to.
This stuff just doesn't get old.
Is there a simple exchange of parts to bias at 200mA? Heat-sink is not an issue, many in spare parts on hand.
Toshiba JFET's for signal were requested to be matched at 8 IDSS, trusted vendor.
Transformer is probably the originally listed 15V / 50. If that's not enough current, I can order a 100.
Many thanks!
Toshiba JFET's for signal were requested to be matched at 8 IDSS, trusted vendor.
Transformer is probably the originally listed 15V / 50. If that's not enough current, I can order a 100.
Many thanks!
The parallel 2x18Ω 2W current setting resistors per side as listed in the "Ten Years After" BOM do bias the integrated shunt PSU at around 200mA per polarity. 50VA 15+15 VAC transformer is covering that with a royal margin. Heat dissipation from the Mosfets is not terrible yet, quite manageable. About two Watt each.
It will fit in a 2U and will not need sinks at 200mA setting if you will utilize the chassis floor as a big sinking plate. With Insulators between the Mosfets and the chassis floor.
Linear Systems LSK170 Quad Idss
I see these are available in the diyAudio store, but there are 6 - 8 mA and 8 - 11 mA. Which is the one I should order for the Mesmerizer. Like others there are some transistors I am having trouble sourcing such as BC550CTA and IRFP240PBF, but BC560CTA seems to be obsolete. Has a replacement for that one been determined?
I see these are available in the diyAudio store, but there are 6 - 8 mA and 8 - 11 mA. Which is the one I should order for the Mesmerizer. Like others there are some transistors I am having trouble sourcing such as BC550CTA and IRFP240PBF, but BC560CTA seems to be obsolete. Has a replacement for that one been determined?
8-11mA IDSS ones for better transconductance. Dissipation will be max 110mW each for DCB1's +/-10V rails even if chancing on the 11mA samples. Still safe.
Use BC549BTA & BC559BTA instead. I see them available on Mouser. I see IRFP240PBF on Future Electronics too. IRFP140NPBF will also work.
Use BC549BTA & BC559BTA instead. I see them available on Mouser. I see IRFP240PBF on Future Electronics too. IRFP140NPBF will also work.
Thanks I ordered the Linear Systems JFETs and the BC549, the BC550 is back ordered as is IRF240PBF and KEMET R82DC3100AA50J.
Mezmerize +-17v ?
Hi,
I would like to use the buffer with high output DAC to drive pass low gain amps. (f5 etc.) Higher rails would be an advantage.
I have a few hundred 2sk209gr, and at approx 3mA i was going to use parallel
. With small resister this should be comfortably within device dissipation max.
At the moment Regulator has 23.5 ohm current set R. and decent heat sink.
Can I simply replace string of 5 LEDS with 1N4745A 16v 1w Zener or add 4 more LEDS to string?
Many thanks.
Hi,
I would like to use the buffer with high output DAC to drive pass low gain amps. (f5 etc.) Higher rails would be an advantage.
I have a few hundred 2sk209gr, and at approx 3mA i was going to use parallel
. With small resister this should be comfortably within device dissipation max.
At the moment Regulator has 23.5 ohm current set R. and decent heat sink.
Can I simply replace string of 5 LEDS with 1N4745A 16v 1w Zener or add 4 more LEDS to string?
Many thanks.
If for higher rails the JFETs dissipation is still kept within reason its OK (near max is not long term trouble free, better derate). Maybe more consistent with the standard design is to add Leds than setting it up with a Zener which is usually noisier below the 1/F knee region.