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Re: Latching Relay Drivers
On Saturday 30 November 2024 09:52:11 am Terry wrote:
BTW, (an aside) the "D" latch becomes a mono stable "flip-flop" when /Q output isNo, that's bistable. -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin |
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my new psu
Hi all, I have just brought this psu,
its o-30v 0-1a,its made of discrete components with no ic's, its transfo has a center tap then +50v,+40v/-50v+-40v taps with a seperate 6.3v winding , the main voltage pot is a 1k with just the center and one outer leg used,its 1k at max volts,would it be possible to mod this for say 2amps and 70 ish volts output? would anyone have any ideas ie schematics etc,or an explanation of its circcuit topolagy,it has a wirewound resistor of 1 ohm,i assume that is a current sense resistor,i have uploaded some pics of it in the photos section called my psu,cheers in advance 73 Paul de m3vuv. |
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Added photo album my psu
#photo-notice
Group Notification
paul larner <quadzillatech@...> added the photo album my psu : my psu pics |
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Re: Latching Relay Drivers
On Saturday 30 November 2024 07:52:01 am Andy via groups.io wrote:
A point that I didn't address in my earlier reply. You've gotta do *something* with those set and reset pins. A power on reset signal would probably be a good thing to add to your design. That can be as simple as a resistor and a cap tied to the input of any schmitt-trigger gate's input, the output driving the reset line.Important points being that outputs are low upon turn on, ...I think not.? Most if not all flip-flops come up in a random state when powered-up.? (Chances are they have a bias for one or the other, but that is not a design feature and should not be counted on.) -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin |
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Re: Latching Relay Drivers
On Saturday 30 November 2024 07:17:08 am Bertho wrote:
It is not what you asked for, but if your relay has extra contacts you can wire it up to be latching and releasing with a separate line.I can see how easy it would be to make a relay latch, but how would you get it to release? -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin |
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Re: Latching Relay Drivers
On Saturday 30 November 2024 02:49:34 am Bob Smith via groups.io wrote:
On 11/29/24 22:36, SheldonD via groups.io wrote:That's why he specified "debounced"...Reaching way back in my mind, I seem to remember JK flip flops toggling output when strobedSo not SET and RESET lines but a single TOGGLE line? -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin |
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Re: Latching Relay Drivers
On Saturday 30 November 2024 01:36:13 am SheldonD via groups.io wrote:
Been playing with various chinese-originated latching relay solutions from Amazon. Most are 'overly optimistic' about capabilities. Very 'overly optimistic'. Otherwise the rest have issues operating in environment with heavy canbus, Bluetooth, pwm alternator, 2M xceiver, and brushed engine / HVAC fans.That'll work, also a Type D FF, if you tie the D input to the Not-Q output. Whether high input will trigger it or not depends on the part, they can work either way, check the datasheet (have a look at rtellason.com/ic-generic). I am thinking that can tie outputs to darlington driver array, like ULN2803 or similar. Up to 1/2A current, 50vdc max, designed for inductive loads. Haven't found any information on temperature control yet.Yeah. Just adding a bit of electronics is way cheaper/simpler overall. Incidentally, relay outputs will be controlling multiple isolated power supplies. Need around 16ch of mixed outputs.Stuff like that oughta be easy to find, and dirt cheap. Most of that vintage stuff like that that I had is in boxes out in the garage, destined for the recycler. I was actually using a 386 box for a router/firewall, but found that a dedicated router was a *lot* faster in terms of throughput, and that on a DSL line! -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin |
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Re: Slow cycling LED 'flasher' for model trains
On Friday 29 November 2024 07:35:28 pm wn4isx via groups.io wrote:
We've had several requests over the last few years for LED flashers for model train enthusiasts. One problem with most LED flashers is the go from full off to full on whereas old style caboose, water tower, and crossing gate lights were incandescent and ramped up and down.ff you want to see a bunch of nifty model railroad electronics look up Rob Paisley. I stubled across his pages some time ago, and enjoyed browsing through them. For flashing LEDs on a layout I'd just go with a simple astable, four resistors, two caps, two transistors and you're all set. It should be possible to make things ramp, I'd guess. Maybe by using relatively large capacitors? -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin |
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Re: Light from semiconductor junctions
On Friday 29 November 2024 07:24:12 pm wn4isx via groups.io wrote:
This will be my last post on non-LED semiconductors emitting light.I remember bumping into something weird in certain Yamaha power amplifiers. They used an actual LED as a biasing part. Though this was not in the typical LED case, but more like the sort of glass-bodied case you'd see for a 1N400x rectifier or similar. I'm not sure why they chose this part, not having actually sat and analyzed the circuit, maybe temperature coefficient or something? I know that there were a whole lot of power amps out there that when one output device failed, the rest of them, along with the drivers, and someimes a whole lot more would also fail. This was not the case with those Yamaha amps, you'd blow one device that that was the extent of the failure, pretty solid stuff that was. Another thing that comes to mind is a thing that Forest Mims did one time. He had two LEDs facing each other, and the one that lit would cause the other one to act as a photodiode. I have some radio shack packages with "IR emitter-detector pair" in them, and an assortment of phototransistors pulled from scrapping VCRS (there's at least two in every VHS machine) and some other parts salvaged from floppy drives, where they are used for write protect and index hole sensing. I haven't found any particular use for these parts, maybe I just haven't found the right inspiration yet... -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin |
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Re: Latching Relay Drivers
¿ªÔÆÌåÓýIt's sounds like you're trying for an
electronic solution to a simple series of 16 "pulse ON, pulse OFF"
latching relays? Where a relay is turned on with an "ON" pulse,
then stays ON until it receives an "OFF" pulse, where it remains
until the next "ON" pulse occurs.
Several possibilities present themselves: use a "toggle" flip-flop like you suggest, (J and K connected together, Q toggles on clock), The problem with that is one of switch de-bounce. Another solution might be a "D" style register, where Q output remains stable based on the last state clocked into the D input. That solution requires a common clock be applied to "set" the ON/OFF condition of the outputs...which are latched until the next clock cycle. A big advantage of this solution is four, six, or even eight latches can be contained in a single IC. BTW, (an aside) the "D" latch becomes a mono stable "flip-flop" when /Q output is tied to the "D" input and clock cycled. Due to the size of the relay array, this is most easily resolved with a small microcontroller. Is that a possible solution? One question, do the relays in your array need to remain in their "last ON" state during a power cycle, or can they simple be reset to "OFF" when the power recycles? The output of the simulated relay is pretty easy, use a high side switch. These utilize a low logic level input to control a much higher positive source switch, usually a P channel FET. That way, CMOS or TTL level inputs can control high power positive switched loads like lights, motors or "large load" resistive. A simple solution would be to find a high side switch with latching capabilities. (Goggle "high side switch") So, guess it all starts (as always) with an exact operational definition of your system's input and output requirement? On 11/30/2024 12:36 AM, SheldonD via groups.io wrote: Been playing with various chinese-originated latching relay solutions from Amazon. Most are 'overly optimistic' about capabilities. Very 'overly optimistic'. Otherwise the rest have issues operating in environment with heavy canbus, Bluetooth, pwm alternator, 2M xceiver, and brushed engine / HVAC fans. |
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Re: Latching Relay Drivers
On Sat, Nov 30, 2024 at 01:36 AM, SheldonD wrote:
Been playing with various chinese-originated latching relay solutions from Amazon. I guess these are electronic latching circuits for driving a relay - not physical latching relays.? You can get latching relays that use no electronics.? I never used one.
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Reaching way back in my mind, I seem to remember JK flip flops toggling output when strobed if J&K are tied high. Maybe it wasn't JK, but another type? You are correct.? JK flip-flops toggled with every clock when both J and K inputs were high.? I always thought that was a weird way to make a flip-flop, and I was happy to learn that they became uncommon.? The more common D flip-flop does the same thing by tying the D input to the Q-bar (inverted Q) output.
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Important points being that outputs are low upon turn on, ... I think not.? Most if not all flip-flops come up in a random state when powered-up.? (Chances are they have a bias for one or the other, but that is not a design feature and should not be counted on.)
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... I do know that relays / contractors that utilize magnets for latch hold are probitive physically and way overkill. Back in the day, they were not hugely expensive, but they might have become that.? As for overkill?? Not if it achieves your aims; that's not overkill.
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Andy
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Re: Latching Relay Drivers
It is not what you asked for, but if your relay has extra contacts you can wire it up to be latching and releasing with a separate line.
toggle quoted message
Show quoted text
Bertho -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of SheldonD via groups.io Sent: 30 November, 2024 1:36 To: [email protected] Subject: [electronics101] Latching Relay Drivers Been playing with various chinese-originated latching relay solutions from Amazon. Most are 'overly optimistic' about capabilities. Very 'overly optimistic'. Otherwise the rest have issues operating in environment with heavy canbus, Bluetooth, pwm alternator, 2M xceiver, and brushed engine / HVAC fans. Reaching way back in my mind, I seem to remember JK flip flops toggling output when strobed if J&K are tied high. Maybe it wasn't JK, but another type? Important points being that outputs are low upon turn on, and stroking with momentary (debounced) switch (high input). I am thinking that can tie outputs to darlington driver array, like ULN2803 or similar. Up to 1/2A current, 50vdc max, designed for inductive loads. Haven't found any information on temperature control yet. Not sure if I am reinventing the wheel. I do know that relays / contractors that utilize magnets for latch hold are probitive physically and way overkill. Incidentally, relay outputs will be controlling multiple isolated power supplies. Need around 16ch of mixed outputs. Suggestions or alternatives if I am on wrong path? Tomorrow I will be trying to find 32/64 bit versions of LTSpice (or similar) as my 486DX4 based PC (500MB drive and 8MB Ram!) 16/32bit machine died during Hurricane Beryl. ~SD |
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Re: Latching Relay Drivers
On 11/29/24 22:36, SheldonD via groups.io wrote:
Reaching way back in my mind, I seem to remember JK flip flops toggling output when strobedSo not SET and RESET lines but a single TOGGLE line? That is tricky since you may get ringing or noise on the line. Use separate lines if possible. Everything else, USN2308 etc, sounds good. Bob |
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Latching Relay Drivers
Been playing with various chinese-originated latching relay solutions from Amazon. Most are 'overly optimistic' about capabilities. Very 'overly optimistic'. Otherwise the rest have issues operating in environment with heavy canbus, Bluetooth, pwm alternator, 2M xceiver, and brushed engine / HVAC fans.
Reaching way back in my mind, I seem to remember JK flip flops toggling output when strobed if J&K are tied high. Maybe it wasn't JK, but another type? Important points being that outputs are low upon turn on, and stroking with momentary (debounced) switch (high input). I am thinking that can tie outputs to darlington driver array, like ULN2803 or similar. Up to 1/2A current, 50vdc max, designed for inductive loads. Haven't found any information on temperature control yet. Not sure if I am reinventing the wheel. I do know that relays / contractors that utilize magnets for latch hold are probitive physically and way overkill. Incidentally, relay outputs will be controlling multiple isolated power supplies. Need around 16ch of mixed outputs. Suggestions or alternatives if I am on wrong path? Tomorrow I will be trying to find 32/64 bit versions of LTSpice (or similar) as my 486DX4 based PC (500MB drive and 8MB Ram!) 16/32bit machine died during Hurricane Beryl. ~SD |
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Slow cycling LED 'flasher' for model trains
wn4isx
We've had several requests over the last few years for LED flashers for model train enthusiasts. One problem with most LED flashers is the go from full off to full on whereas old style caboose, water tower, and crossing gate lights were incandescent and ramped up and down. ? If you look at brake lights on cars in traffic it is easy to see this effect, the LED brake lights come on instantly and the incandescent ramp up when turned on and down when turned off. ? I have no idea what degree of realism model train types want or can achieve. ? I remember with my model trains as a child I was unhappy with the 'acceleration curve,' you went from standstill to ~20MPH. And yes I know there are better controllers today. ? http://cappels.org/dproj/1.5V_Red_fader_blinker/1.5_volt_1970%27s_style_caboose_marker_flashing_led_light.html ? There is a short MOV you can download to see if the effect is what you want. ? [I stumbled on this by accident and can offer no advice.] ? |
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Light from semiconductor junctions
wn4isx
This will be my last post on non-LED semiconductors emitting light. ? First, all of the forward biased semiconductors I tested emitted light. The glass cased silicon diodes were the easiest to verify, I chopped the tops of several TO-3 and TO-5 transistors. All of the emitted light required a night vision (starlight) scope to see. 4th vision nightvision scopes have between 25,000-110,000 gain, the exact gain figures are apparantly restricted by ITAR [International Traffic in Arms Regulations]. ? However reverse biased semiconductor junctions are a different story. I'll admit I was pleasantly surprised.... ? A friend gave me this link. Interesting to be sure but I doubt it's practical. http://cappels.org/dproj/Avalanche_Photogenerator/Avalanche_Breakdown_Photoemission_and_the_Photoelectric_Effect_in_Bipolar_Transistors.html ? And it might be worthwhile to follow the links here
? This image is fascinating and I was able to come very close image with a 1980s 2N2222 with the top removed. ?
This light is clearly visible in a dark room. ? ? I sacrificed 3 2N3055s. These were older RCA units with excessive leakage. All 3 emitted nice light when the collector to base junction was reverse biased to break down. Note: Limit breakdown current to a few mA.? This has been an interesting, if relatively useless experiment. ? ? ? |
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Re: aliexpress freq counters views
On Thu, Nov 28, 2024 at 11:03 AM, Roy J. Tellason, Sr. wrote:
And yet they give you eight digits? And claim to be usable up to 1200MHz? I think I'll pass... Sometimes having lots of digits can be helpful, even when it does not mean precision accuracy.? Then it is up to the user of the instrument to interpret it correctly.
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For example, when making comparative frequency measurements.? The more digits, the better.
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1200 MHz might be do-able, but most likely sensitivity suffers at that end.
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Andy
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Bertho
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