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ε24 Rebooted

epsilon24

ε24 Rebooted

Postby sv511 » January 14th, 2016, 6:24 am

While I'm waiting for σ22 parts to arrive from glass jar audio, I've been thinking about the rest of the build.

I like the ε24. Instead of building one from a kit, I decided to re-do the design for fun.


I'm working on some ideas around a MAX16054.


I'll try and post a schematic in the next day or so.
Last edited by sv511 on January 15th, 2016, 3:39 am, edited 1 time in total.

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Re: ε24 Rebooted

Postby sv511 » January 15th, 2016, 12:01 am

This is a simple on-off switch without thermal protection. Thermal shutdown using the clear pin is next.

The CMOS outputs can source 0.4mA and sink 1.6mA. That is enough to drive a low-power SSR from !OUT.

X2 connects to a lighted normally open push button switch.

X3 connects to a larger power relay. The CPC1017N can switch a 100mA DC load. My goal is to make this work with a surface mount 7805 but I haven't done any of the power estimates yet.



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Re: ε24 Rebooted

Postby amb » January 15th, 2016, 3:17 am

Looks like MAX16054 is a perfect chip for this.

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Re: ε24 Rebooted

Postby sv511 » January 15th, 2016, 3:38 am

Here is a version with temperature protection. A normally open thermal switch connects to X4. Closing the thermal switch pulls CLEAR high and turns on the over temp LED.

Pulling CLEAR high resets an internal flip-flop, setting !OUT high de-energising K1. Unlike the ε24, the device will not turn back on when the thermal switch resets.

I haven't decided if I want to make it work with a red/blue Bulgin switch.

I'm going to figure out resistor values and power dissipation in the 7805 next. After that, I'm going to do a quick layout to get a better idea of the size. My primary constraint on the layout is staying within 100x100mm. A secondary goal would be matching the ε24 footprint.


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Re: ε24 Rebooted

Postby passive420 » January 17th, 2016, 4:18 am

Thanks for this, I'd like to try your circuit. Do you know of similar parts in PDIP packages? - I have found SOT-23 Brown Dog adapters for MAX16054 and would IXYS LCA125 be suitable?

I actually wanted to play with a 5V switched SSR circuit using an optocoupler and triac to switch power amp, I just needed a safe switch circuit with debounce.

Your PCB's would be ideal if you can include footprint for EI-30 PCB-mount transformer.
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Re: ε24 Rebooted

Postby sv511 » January 17th, 2016, 10:13 am

I'm not aware of anything in PDIP that has the entire functionality of the MAX16054. The legacy MC14490 hex contact debouncer is probably still available in PDIP. I haven't checked. But that doesn't do the latching. You'd need a flip-flop or something similar.


A 6-pin SOT-23 pins are .95mm apart. I use nothing more than an ancient Weller soldering station an a pair of good tweezers. I'll admit it is right at the limit of what I can do.


I'll have to look up the IXYS relay and get back to you.

I am working on PCB layouts now. I've got something that is 1.2 inches x 100mm. I will probably cut that down to 1.2 x 3.9 inches. My initial constraint was staying inside the limit for inexpensive boards from PCBway. I'll post up a layout for review when I'm ready.

Need to check with the forum admin before I offer up any extra boards. I'll make them available only with permission.


http://www.onsemi.com/pub_link/Collateral/MC14490-D.PDF

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Re: ε24 Rebooted

Postby passive420 » January 17th, 2016, 2:53 pm

If everything goes well and with approval I would be very interested in your boards Sir. This really is exactly what I'm looking for.

Yeah, this needs to be breadboarded for my own learning/enjoyment. I'm OK for the CMOS part as there are SOT-23 adapters but SOP4 part is a rare one. I'll try the PDIP LCA125 as it should work ok, it's a heavier duty part with the same gate sensitivity by the looks.
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Re: ε24 Rebooted

Postby amb » January 17th, 2016, 2:57 pm

sv511 wrote:Need to check with the forum admin before I offer up any extra boards. I'll make them available only with permission.

If you're only getting a few pieces and sell the extras to fellow DIYers as a one-time thing, then I have no problem with it. Use the For Sale/Want to buy subforum for this.

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Re: ε24 Rebooted

Postby passive420 » January 17th, 2016, 5:28 pm

Actually, with the Triac circuit I wish to implement below, I can likely omit the IXYS relay and use the MAX16054 to fire my chosen optocoupler, which has the same gate sensitivity.

Oh, for your design would a more efficient LDO such as LT1086 5V be a better part? It has one volt less dropout and comes in DDpak, iIt could therefore be powered with 6V AC supply instead of 9V

http://cds.linear.com/docs/en/datasheet/1086ffs.pdf
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Re: ε24 Rebooted

Postby sv511 » January 18th, 2016, 12:08 am

The maximum current through the regulator is about 101mA. I wasn't too worried about the power dissipation or voltage drop across a TO-220 LM7805.

One thing I considered was driving the off board relay with unregulated power. I could use a TO-92 or SOT-23 package regulator for the logic. I could either use a second regulator or a higher value current limit resistor for the power-on LED.

I'll need to look at the off board relays before making a decision.

An LT1086 would dissipate less power and a simple drop-in if you want to use one.
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